1645 IoT Glossary: G-P
Essential IoT Terms from Gateway to Publisher
This is Part 2 of the IoT Glossary, covering terms G-P. See also:
- IoT Glossary Index - Overview and quick navigation
- Glossary A-F - ACL through Frame
- Glossary Q-Z - QoS through 6LoWPAN
1645.1 Learning Objectives
After reviewing this section, you should be able to:
- Define key IoT terms from G to P with technical accuracy
- Distinguish between commonly confused concepts (e.g., gateway vs. router, I2C vs. SPI)
- Understand messaging patterns including publishers, subscribers, and topics
- Identify appropriate protocols and hardware interfaces for different IoT scenarios
1645.2 G
1645.2.1 Gateway
Definition: A device that connects networks using different protocols, translating between them and enabling communication between IoT devices and external networks or cloud services.
In simple terms: A translator between different languages - connects your Zigbee sensors to your Wi-Fi network by translating between the two “languages” they speak.
Common confusions: - Gateway vs. router - gateways translate protocols, routers only forward packets - IoT gateways often combine routing, protocol translation, and edge processing
Related terms: Edge Computing, Broker, Middleware
Synonyms: IoT gateway, protocol converter, edge gateway
1645.2.2 GPIO (General Purpose Input/Output)
Definition: Programmable digital pins on a microcontroller that can be configured as either inputs (reading signals) or outputs (sending signals) for interfacing with external components.
In simple terms: The connection points on a microcontroller - like USB ports on a computer, but simpler and more flexible, letting you connect sensors, LEDs, buttons, and other hardware.
Common confusions: - GPIO is digital only - use ADC for analog input - GPIO pin current limits must be respected to avoid damage
Related terms: ADC, DAC, Microcontroller, I2C
Synonyms: digital pins, I/O pins
1645.3 H
1645.3.1 HTTP (Hypertext Transfer Protocol)
Definition: The foundation protocol of the web, using request-response communication over TCP to transfer hypertext documents, APIs, and other resources between clients and servers.
In simple terms: The language of the web - how your browser asks for web pages and receives them, also used by many IoT devices to send data to cloud services.
Common confusions: - HTTP vs. HTTPS - HTTPS adds TLS encryption for security - HTTP/1.1 vs. HTTP/2 vs. HTTP/3 have significant performance differences
Related terms: HTTPS, REST, API, CoAP
Synonyms: web protocol
1645.3.2 HTTPS (HTTP Secure)
Definition: HTTP protocol secured with TLS encryption, ensuring confidentiality, integrity, and authentication for web communications through cryptographic protection.
In simple terms: Secure HTTP - the same web protocol but wrapped in encryption so nobody can eavesdrop on or tamper with your data in transit.
Common confusions: - HTTPS requires certificates and adds computational overhead - Not all IoT devices support HTTPS due to resource constraints
Related terms: HTTP, TLS, Certificate, Encryption
Synonyms: HTTP over TLS, secure HTTP
1645.4 I
1645.4.1 I2C (Inter-Integrated Circuit)
Definition: A synchronous serial communication bus using two wires (data and clock) to connect multiple peripheral devices to a microcontroller, with addressing supporting up to 127 devices.
In simple terms: A shared communication line - multiple sensors and devices can talk to one microcontroller using just two wires, taking turns like people on a conference call.
Common confusions: - I2C vs. SPI - I2C needs fewer wires but is slower, SPI is faster but needs more wires - I2C addresses must be unique on each bus (some devices have configurable addresses)
Related terms: SPI, UART, GPIO, Microcontroller
Synonyms: IIC, TWI (Two-Wire Interface)
1645.4.2 Idempotency
Definition: A property of operations where performing them multiple times produces the same result as performing them once, enabling safe retries without unintended side effects.
In simple terms: “Press as many times as you want” - like an elevator button that does the same thing whether you press it once or ten times.
Common confusions: - GET is idempotent, POST typically is not - Idempotency keys help make non-idempotent operations safely retriable
Related terms: At-least-once, Retry, Exactly-once
Synonyms: idempotent operation
1645.4.3 InfluxDB
Definition: An open-source time series database optimized for fast, high-availability storage and retrieval of time-stamped data, commonly used for IoT metrics, monitoring, and analytics.
In simple terms: A database built for sensor data - specifically designed to handle the millions of time-stamped readings that IoT devices generate, with efficient storage and fast queries.
Common confusions: - InfluxDB vs. relational databases - InfluxDB optimizes for time-based queries, not relationships - InfluxQL vs. Flux query languages have different capabilities
Related terms: TSDB, TimescaleDB, Time Series, Telemetry
Synonyms: none common
1645.5 J
1645.5.1 Jitter
Definition: The variation in delay between packets arriving at a destination, causing inconsistency in data arrival times that can affect real-time applications and time-sensitive systems.
In simple terms: Inconsistent timing - like a musician who can’t keep a steady beat, packets arrive at irregular intervals even if the average delay is acceptable.
Common confusions: - Jitter vs. latency - latency is average delay, jitter is variation in delay - High jitter is problematic even with low average latency
Related terms: Latency, Bandwidth, QoS
Synonyms: packet delay variation (PDV)
1645.5.2 JSON (JavaScript Object Notation)
Definition: A lightweight, human-readable data interchange format using key-value pairs and arrays, widely used for API communication and configuration in IoT systems.
In simple terms: A universal data format - a simple way to structure data that both humans can read and machines can process, like a common language everyone understands.
Common confusions: - JSON is text-based (larger than binary formats like CBOR or Protobuf) - JSON lacks native support for binary data (must encode as Base64)
Related terms: CBOR, Protobuf, Payload, Serialization
Synonyms: none common
1645.6 L
1645.6.1 Latency
Definition: The time delay between initiating a request and receiving a response, measured in milliseconds, representing how long data takes to travel through a system or network.
In simple terms: Response time - how long you wait between pressing a button and seeing the result, like the delay between flipping a light switch and the light turning on.
Common confusions: - Low latency vs. high bandwidth - you can have fast response with limited throughput or vice versa - Network latency is just one component of end-to-end latency
Related terms: Bandwidth, Jitter, Edge Computing
Synonyms: delay, response time, lag
1645.6.2 LoRa (Long Range)
Definition: A proprietary spread spectrum modulation technique derived from chirp spread spectrum (CSS) technology, enabling long-range, low-power wireless communication for IoT devices.
In simple terms: A radio technology for distance - sends data over miles using very little power, perfect for sensors in remote locations that need to communicate without Wi-Fi or cellular coverage.
Common confusions: - LoRa vs. LoRaWAN - LoRa is the physical layer modulation, LoRaWAN is the network protocol on top - LoRa is proprietary to Semtech, not an open standard
Related terms: LoRaWAN, NB-IoT, LTE-M
Synonyms: LoRa modulation, CSS
1645.6.3 LoRaWAN
Definition: An open network protocol specification built on LoRa physical layer, defining the network architecture, security, and communication protocols for wide-area IoT deployments.
In simple terms: The complete network system using LoRa - includes not just the radio technology but the whole setup of gateways, servers, and security that creates a working IoT network.
Common confusions: - LoRaWAN vs. LoRa - LoRaWAN is the complete protocol stack, LoRa is just the modulation - Three device classes (A, B, C) offer different latency/power tradeoffs
Related terms: LoRa, NB-IoT, LPWAN, Gateway
Synonyms: Long Range Wide Area Network
1645.6.4 LPWAN (Low Power Wide Area Network)
Definition: A type of wireless network designed to allow long-range communication at low bit rates among connected devices, optimized for battery-powered IoT applications.
In simple terms: Networks for simple, long-range devices - designed for sensors that send small amounts of data over long distances while running on batteries for years.
Common confusions: - LPWAN is a category, not a specific technology (includes LoRaWAN, Sigfox, NB-IoT) - LPWAN trades bandwidth for range and power efficiency
Related terms: LoRaWAN, NB-IoT, LTE-M, Sigfox
Synonyms: low power network, wide area IoT
1645.6.5 LTE-M (LTE for Machines)
Definition: A cellular IoT technology based on LTE networks, providing moderate bandwidth, mobility support, and voice capability for IoT devices requiring higher data rates than NB-IoT.
In simple terms: Cellular for IoT with more features - uses existing cell towers to connect IoT devices, with enough bandwidth for things like wearables that need more data than simple sensors.
Common confusions: - LTE-M vs. NB-IoT - LTE-M has higher bandwidth and mobility support, NB-IoT is simpler and lower power - LTE-M supports VoLTE for voice applications
Related terms: NB-IoT, LPWAN, Cellular IoT
Synonyms: Cat-M1, eMTC
1645.7 M
1645.7.1 Matter
Definition: A unified, IP-based connectivity standard for smart home devices, developed by the Connectivity Standards Alliance to enable interoperability across ecosystems (Apple, Google, Amazon).
In simple terms: The universal smart home language - finally allows devices from different brands to work together seamlessly, like a translator that lets Apple, Google, and Amazon devices all communicate.
Common confusions: - Matter doesn’t replace Wi-Fi or Thread - it runs over them as transport - Matter certification ensures interoperability but doesn’t guarantee all features work across platforms
Related terms: Thread, Zigbee, Wi-Fi
Synonyms: Project CHIP (original name)
1645.7.2 Mesh
Definition: A network topology where devices connect directly to multiple other devices, creating redundant paths that improve reliability and extend coverage through multi-hop routing.
In simple terms: A web of connections - every device can talk to multiple neighbors and messages hop from device to device, so if one path fails, data finds another route.
Common confusions: - Mesh vs. star topology - mesh has multiple paths, star has single central connection - Mesh increases reliability but adds complexity and latency
Related terms: Star Topology, Routing, Zigbee, Thread
Synonyms: mesh network, mesh topology
1645.7.3 Metadata
Definition: Data that provides information about other data, such as timestamps, device identifiers, data types, units, and quality indicators that contextualize the primary payload.
In simple terms: Information about information - the label on a package that tells you what’s inside, when it was sent, and where it came from, without being the actual contents.
Common confusions: - Metadata vs. payload - metadata describes, payload contains actual values - Metadata is essential for data management but adds overhead
Related terms: Payload, Timestamp, Schema
Synonyms: meta-information, data context
1645.7.4 Microcontroller
Definition: A compact integrated circuit containing a processor, memory, and programmable I/O peripherals, designed for embedded applications and IoT devices with specific control functions.
In simple terms: A tiny computer on a chip - contains everything needed to run simple programs and control hardware, perfect for IoT devices that need to be small, cheap, and power-efficient.
Common confusions: - Microcontroller vs. microprocessor - microcontrollers include memory and peripherals on-chip - Popular IoT microcontrollers include ESP32, STM32, Arduino-based chips
Synonyms: MCU, embedded controller
1645.7.5 Microservices
Definition: An architectural style that structures an application as a collection of loosely coupled, independently deployable services, each implementing specific business capabilities.
In simple terms: Building with LEGO blocks - instead of one big application, break it into many small, independent services that can be developed, deployed, and scaled separately.
Common confusions: - Microservices vs. monolith - microservices add complexity but improve scalability and maintainability - Microservices require robust communication and orchestration
Related terms: API, Serverless, Platform
Synonyms: microservice architecture
1645.7.6 Middleware
Definition: Software that sits between the operating system and applications, providing common services like messaging, authentication, API management, and data transformation.
In simple terms: The glue between systems - handles the complicated work of connecting different parts of a system so application developers can focus on business logic.
Common confusions: - Middleware vs. API - middleware provides services, APIs provide access to them - IoT middleware often includes message brokers and protocol adapters
Related terms: Broker, API, Gateway
Synonyms: integration layer, message-oriented middleware
1645.7.7 Modbus
Definition: A serial communication protocol originally developed for programmable logic controllers (PLCs), now widely used in industrial IoT for connecting electronic devices.
In simple terms: The industrial standard language - an old but reliable way for factory equipment to communicate, like the standard railroad track gauge that ensures all trains can run on the same rails.
Common confusions: - Modbus RTU (serial) vs. Modbus TCP (Ethernet) have different physical layers - Modbus is simple but lacks built-in security
Related terms: OPC-UA, Industrial IoT, Gateway
Synonyms: Modbus Protocol
1645.7.8 MQTT (Message Queuing Telemetry Transport)
Definition: A lightweight publish-subscribe messaging protocol designed for constrained devices and low-bandwidth, high-latency networks, using a broker to route messages between clients.
In simple terms: The postal service for IoT - devices send messages to a central post office (broker) addressed to topics, and anyone subscribed to those topics receives the messages.
Common confusions: - MQTT doesn’t actually use message queuing despite its name - MQTT 3.1.1 vs. MQTT 5 have significant feature differences
Related terms: Broker, Topic, Publisher, Subscriber, QoS
Synonyms: none common
1645.7.9 MTU (Maximum Transmission Unit)
Definition: The largest size of a protocol data unit that can be transmitted in a single network transaction, determining when packets must be fragmented for transmission.
In simple terms: The maximum package size - like postal limits on how big a box can be, networks have maximum sizes for data chunks before they must be split.
Common confusions: - MTU varies by network type (Ethernet 1500 bytes, 6LoWPAN much smaller) - MTU mismatch can cause connectivity issues
Related terms: Packet, Frame, 6LoWPAN
Synonyms: maximum packet size
1645.8 N
1645.8.1 NB-IoT (Narrowband IoT)
Definition: A cellular IoT technology using a narrow 200kHz bandwidth, providing excellent coverage, low power consumption, and lower cost for simple IoT devices requiring infrequent data transmission.
In simple terms: Cellular for simple sensors - uses existing cell towers to connect basic IoT devices that only need to send small amounts of data occasionally, with amazing battery life.
Common confusions: - NB-IoT vs. LTE-M - NB-IoT is simpler and lower power but has less bandwidth and no mobility - NB-IoT can work in-band, guard-band, or standalone deployments
Related terms: LTE-M, LPWAN, LoRaWAN
Synonyms: LTE Cat-NB1, Cat-NB2
1645.9 O
1645.9.1 OAuth
Definition: An open authorization framework that enables secure delegated access, allowing users to grant third-party applications limited access to their resources without sharing credentials.
In simple terms: “Sign in with Google” for machines - lets you give an app permission to access your data without giving it your password, like giving a valet your car key but not your house key.
Common confusions: - OAuth 2.0 vs. OAuth 1.0 are significantly different (2.0 is not backward compatible) - OAuth is for authorization, not authentication (OpenID Connect adds authentication)
Related terms: Authentication, Authorization, Token
Synonyms: OAuth 2.0
1645.9.2 OPC-UA (OPC Unified Architecture)
Definition: A platform-independent, service-oriented architecture providing secure, reliable data exchange for industrial automation, supporting complex data models and standardized communication.
In simple terms: The modern industrial communication standard - enables factory machines from different vendors to share data securely, with rich information models and enterprise-grade security.
Common confusions: - OPC-UA vs. OPC Classic - UA is platform-independent, Classic was Windows-only - OPC-UA includes security and information modeling that Modbus lacks
Related terms: Modbus, Industrial IoT, Middleware
Synonyms: UA, IEC 62541
1645.10 P
1645.10.1 Packet
Definition: A unit of data at the network layer (Layer 3) containing header information (addresses, protocol) and payload, routed independently across networks toward its destination.
In simple terms: A data envelope with an address - contains the actual message plus delivery information, like a letter with destination address that postal workers use for routing.
Common confusions: - Packet vs. frame - packets are Layer 3 (IP), frames are Layer 2 (Ethernet) - Packets may be fragmented if larger than MTU
Related terms: Frame, Payload, Routing
Synonyms: datagram, IP packet
1645.10.2 Payload
Definition: The actual data being transported within a message or packet, excluding headers, metadata, and protocol overhead - the meaningful content that applications process.
In simple terms: The actual cargo - in a delivery truck (packet), the payload is the goods being delivered, not the truck itself or the shipping labels.
Common confusions: - Payload vs. message - payload is the content portion, message includes headers/metadata - Payload format varies (JSON, CBOR, Protobuf, binary)
Related terms: JSON, CBOR, Packet, Metadata
Synonyms: data payload, message body, content
1645.10.3 Platform
Definition: A comprehensive software environment providing infrastructure services for IoT applications, including device management, data ingestion, storage, analytics, and visualization.
In simple terms: A complete IoT toolkit - provides all the services you need to build IoT applications without starting from scratch, like a fully equipped kitchen versus building your own stove.
Common confusions: - Platform vs. protocol - platforms are complete solutions, protocols are communication standards - Examples: AWS IoT, Azure IoT, Google Cloud IoT, ThingsBoard
Related terms: Cloud, Middleware, Digital Twin
Synonyms: IoT platform, cloud platform
1645.10.4 Protobuf (Protocol Buffers)
Definition: A language-neutral, platform-neutral binary serialization format developed by Google, using predefined schemas to create compact, efficient data structures for communication.
In simple terms: Efficient data packing with blueprints - you define the structure once (schema), then data is packed tightly according to that blueprint, saving space and processing time.
Common confusions: - Protobuf requires schema definition upfront (unlike JSON which is self-describing) - Protobuf is more efficient than JSON but less human-readable
Related terms: JSON, CBOR, Schema, Serialization
Synonyms: Protocol Buffers, pb
1645.10.5 Publisher
Definition: A client in publish-subscribe messaging that sends messages to topics, without knowledge of or direct connection to the subscribers who will receive those messages.
In simple terms: A broadcaster - sends messages into the system addressed to topics, not caring who’s listening, like a radio station that transmits without knowing who has tuned in.
Common confusions: - Publisher vs. producer - essentially the same concept - Publishers are decoupled from subscribers (neither knows about the other)
Related terms: Subscriber, Topic, Broker, MQTT
Synonyms: producer, sender, message source
1645.11 Summary
This section covered 30 essential IoT terms from G through P:
| Category | Terms | Examples |
|---|---|---|
| Protocols | 8 | HTTP, HTTPS, LoRa, LoRaWAN, MQTT, Modbus, OPC-UA |
| Networking | 6 | Gateway, Latency, LPWAN, LTE-M, Mesh, NB-IoT |
| Hardware | 5 | GPIO, I2C, Microcontroller, MTU, Packet |
| Data | 5 | InfluxDB, JSON, Metadata, Payload, Protobuf |
| Architecture | 4 | Matter, Microservices, Middleware, Platform |
| Messaging | 2 | OAuth, Publisher |
| Reliability | 2 | Idempotency, Jitter |
1645.12 What’s Next
Continue to Glossary Q-Z for terms from QoS through 6LoWPAN, including quality of service concepts, security terms (TLS, Token), database technologies (TSDB, TimescaleDB), and wireless protocols (Zigbee, Z-Wave, Thread).