10 IoT Glossary: Terms From S Through V
More
Depth: Practitioner
Progress saves as you read. Mark sections complete as you go; your progress appears in the sidebar.
10.1 Start With the Decision
This section: Start With the Decision — A design review now covers sensors, security, storage, and wireless links.
A design review now covers sensors, security, storage, and wireless links. Clear terms keep those choices precise.
10.2 Route Overview
This section: Route Overview — This is part 1 of 2.
This is part 1 of 2. Continue with IoT Glossary: Terms From W Through Z.
10.3 Part Objectives
This section: Part Objectives
- Test s with a concrete scenario and pass criteria.
- Validate u with a concrete scenario and pass criteria.
10.4 Start With the Situation
This section: Start With the Situation — A design review has moved from routing and reliability to sensors, security, storage, and wireless choices.
A design review has moved from routing and reliability to sensors, security, storage, and wireless choices. This second reference route collects the S-Z vocabulary needed to describe those decisions precisely.
10.5 Overview
This section: Overview — This route covers S-Z terms, connecting sensing and security vocabulary to time-series systems and late-alphabet wireless protocols.
This route covers S-Z terms, connecting sensing and security vocabulary to time-series systems and late-alphabet wireless protocols.
This is part 2 of 2. Review IoT Glossary: Q-R when you need the first route.
10.6 Learning Objectives
This section: Learning Objectives
By the end of this chapter, you will be able to:
- define S-Z IoT terms precisely
- distinguish related sensing, security, and storage terms
- apply wireless and time-series vocabulary in design reviews
10.7 Chapter Roadmap
This section: Chapter Roadmap
- Start With the Situation
- Overview
- S
- T
- Knowledge Check: Choosing the Right Database
- U
10.8 S
This section: S
10.8.1 Sampling
Definition: The process of converting continuous signals into discrete values at regular intervals, with sampling rate determining how often measurements are taken.
In simple terms: Taking periodic snapshots - instead of continuous recording, take measurements at regular intervals, like checking temperature every minute instead of watching a thermometer constantly.
Common confusions:
- To reconstruct a band-limited signal, sampling rate needs to exceed twice the highest frequency of interest; many IoT sensing tasks use lower rates when they only need trends or thresholds
- Higher sampling rates produce more data but may not add value
Related terms: ADC, Time Series, Aggregation
Synonyms: data sampling, signal sampling
10.8.2 Schema
Definition: A formal description of data structure defining field names, types, constraints, and relationships, used to validate data and ensure consistency across systems.
In simple terms: A data template - specifies what fields data should have and what types they should be, like a form that defines required fields and their formats.
Common confusions:
- Schema-on-write vs. schema-on-read have different flexibility/reliability tradeoffs
- Schema evolution needs versioning and compatibility rules so older devices and newer services can coexist
Related terms: JSON, Protobuf, Serialization
Synonyms: data schema, data model
10.8.3 Sensor
Definition: A device that detects and measures physical properties (temperature, light, motion, pressure) and converts them into electrical signals that can be processed by electronic systems.
In simple terms: The eyes and ears of IoT - devices that measure the real world and report what they sense, like a thermometer that tells a computer what the temperature is.
Common confusions:
- Sensor vs. transducer - sensors measure, transducers convert energy forms (sensors are a type of transducer)
- Sensor accuracy vs. precision are different characteristics
Related terms: Actuator, ADC, Telemetry
Synonyms: detector, transducer
10.8.4 Serialization
Definition: The process of converting data structures or objects into a format suitable for storage or transmission, enabling reconstruction of the original structure later (deserialization).
In simple terms: Packing for shipment - converting complex data into a flat format that can be sent over a network or saved to disk, then unpacking it at the destination.
Common confusions:
- Serialization format affects size, speed, and compatibility (JSON vs. CBOR vs. Protobuf)
- Deserialization needs validation for malformed, oversized, or malicious data
Related terms: JSON, CBOR, Protobuf, Payload
Synonyms: marshalling, encoding
10.8.5 Serverless
Definition: A cloud computing execution model where the cloud provider dynamically manages server allocation, charging only for actual execution time, abstracting infrastructure management.
In simple terms: Computing without managing servers - write code that runs when needed without worrying about servers, scaling, or paying for idle time, like renting a taxi versus owning a car.
Common confusions:
- Serverless still uses servers, you just don’t manage them
- Cold start latency can affect time-sensitive applications
Related terms: Cloud, Microservices, Platform
Synonyms: Function as a Service (FaaS), Lambda
10.8.6 Sigfox
Definition: A proprietary LPWAN technology using ultra-narrowband modulation for very low-power, low-throughput IoT communication, associated with operated network services where coverage is available.
In simple terms: A managed low-data IoT network - like a phone-network model for simple sensors, intended for devices that send very small payloads infrequently.
Common confusions:
- Sigfox is network-as-a-service (you don’t deploy your own infrastructure)
- Very limited uplink payload size and daily message count in common Sigfox service profiles
Related terms: LPWAN, LoRaWAN, NB-IoT
Synonyms: none common
10.8.7 SoC (System on Chip)
Definition: An integrated circuit that combines a processor, memory, I/O interfaces, and often wireless connectivity into a single chip, providing complete computing functionality for embedded systems.
In simple terms: An entire computer on one chip - everything from the processor to Wi-Fi radio combined into a single piece of silicon, making it easy to build small, integrated devices.
Common confusions:
- SoC vs. microcontroller - SoCs typically include more features like wireless, microcontrollers are simpler
- Examples: ESP32, Nordic nRF52, Raspberry Pi RP2040
Related terms: Microcontroller, GPIO
Synonyms: System on a Chip, integrated SoC
10.8.8 SPI (Serial Peripheral Interface)
Definition: A synchronous serial communication interface using four wires (clock, data in, data out, select) for high-speed communication between a microcontroller and peripheral devices.
In simple terms: Fast wired communication - uses more wires than I2C but is faster, good for sensors and displays that need to transfer lots of data quickly.
Common confusions:
- SPI vs. I2C - SPI is faster but needs more wires and individual select lines per device
- SPI has multiple modes (CPOL/CPHA) that need to match between devices
Related terms: I2C, UART, GPIO
Synonyms: four-wire serial bus
10.8.9 Star Topology
Definition: A network topology where all devices connect to a central hub or coordinator, with all communication flowing through this central point rather than directly between devices.
In simple terms: Hub-and-spoke design - every device connects to one central point, like streets radiating from a town center. Simple, but the center becomes a critical dependency.
Common confusions:
- Star vs. mesh - star is simpler but less resilient, mesh has redundant paths
- Wi-Fi networks typically use star topology with the access point as center
Related terms: Mesh, Routing, Gateway
Synonyms: hub topology, centralized topology
10.8.10 Subscriber
Definition: A client in publish-subscribe messaging that registers interest in specific topics and receives messages published to those topics, without direct connection to publishers.
In simple terms: A listener - signs up to receive certain types of messages from the system, like subscribing to a newsletter to receive updates on topics you care about.
Common confusions:
- Subscriber vs. consumer - essentially the same concept
- Subscribers are decoupled from publishers (don’t know who’s sending)
Related terms: Publisher, Topic, Subscription, Broker
Synonyms: consumer, receiver, listener
10.8.11 Subscription
Definition: A registration with a message broker expressing interest in messages matching a topic filter, retained for the MQTT session and removed by unsubscribe, session expiry, or a new clean session.
In simple terms: A standing order for messages - tell the broker “send me anything about topic X” and you’ll receive matching messages while your session keeps that subscription.
Common confusions:
- Subscription vs. topic - subscription is the registration, topic is what you subscribe to
- Durable vs. non-durable subscriptions persist (or not) across disconnections
Related terms: Topic, Subscriber, Filter, Wildcard
Synonyms: topic subscription
10.9 T
This section: T
10.9.1 Telemetry
Definition: The automated collection and transmission of measurements from remote devices to receiving equipment for monitoring, including sensor readings, status information, and performance metrics.
In simple terms: Remote sensing data - the continuous stream of measurements sent from devices in the field back to a central system, like vital signs monitors sending patient data to nurses’ stations.
Common confusions:
- Telemetry vs. commands - telemetry flows from devices, commands flow to devices
- Telemetry vs. logs - telemetry is structured measurements, logs are event records
Related terms: Sensor, Time Series, MQTT
Synonyms: device telemetry, sensor data, metrics
10.9.2 Thread
Definition: An IPv6-based mesh networking protocol designed for smart home devices, providing secure, low-power communication with mesh routing and border-router connectivity.
In simple terms: Modern smart home mesh - a low-power way for home devices to communicate using IPv6, often used as a network transport for Matter devices.
Common confusions:
- Thread vs. Zigbee - Thread uses IP, Zigbee has its own network layer
- Thread is a transport for Matter (they work together)
Related terms: Matter, Mesh, 6LoWPAN, Zigbee
Synonyms: Thread Group protocol
10.9.3 Throughput
Definition: The actual rate at which data is successfully transferred over a network connection, typically lower than bandwidth due to protocol overhead, errors, and congestion.
In simple terms: Real-world speed - while bandwidth is the maximum theoretical capacity, throughput is how fast data actually moves in practice, accounting for all the overhead and delays.
Common confusions:
- Throughput vs. bandwidth - throughput is achieved rate, bandwidth is capacity
- Throughput varies based on conditions, bandwidth is a fixed characteristic
Related terms: Bandwidth, Latency
Synonyms: actual speed, effective bandwidth
10.9.4 Time Series
Definition: A sequence of data points indexed by time, commonly used in IoT for recording sensor measurements, metrics, and events with timestamps for temporal analysis.
In simple terms: Data ordered by time - measurements collected over time, like temperature readings every minute, stored in time order so you can see trends and patterns.
Common confusions:
- Time series databases are optimized differently than relational databases
- Time series data often requires special handling for gaps and irregular intervals
Related terms: TSDB, Telemetry, Timestamp, Aggregation
Synonyms: temporal data, time-stamped data
10.9.5 TimescaleDB
Definition: An open-source time series database built on PostgreSQL, combining full SQL support with time series optimizations for IoT, monitoring, and analytics workloads.
In simple terms: SQL-friendly time series database - handles sensor data efficiently while letting you use familiar SQL queries and benefiting from PostgreSQL’s ecosystem.
Common confusions:
- TimescaleDB vs. InfluxDB - TimescaleDB uses SQL, InfluxDB has its own query languages
- TimescaleDB is an extension to PostgreSQL, not a standalone database
Related terms: TSDB, InfluxDB, Time Series
Synonyms: none common
10.9.6 Timestamp
Definition: A recorded point in time associated with data, typically expressed in a standardized format like Unix epoch time or ISO 8601, essential for ordering and correlating events.
In simple terms: A date-time stamp - marks when something happened, like the postmark on a letter, essential for knowing when sensor readings were taken.
Common confusions:
- Timestamp precision matters (seconds vs. milliseconds vs. microseconds)
- Timezone handling is crucial for distributed systems
Related terms: Time Series, Metadata, Telemetry
Synonyms: datetime, epoch time
10.9.7 TLS (Transport Layer Security)
Definition: A cryptographic protocol providing secure communication over networks through encryption, authentication, and integrity verification, the successor to SSL.
In simple terms: The “S” in HTTPS - encrypts data in transit so eavesdroppers can’t read it, verifies server identity, and ensures data hasn’t been tampered with.
Common confusions:
- TLS vs. SSL - TLS is the modern successor, SSL is deprecated
- TLS works with TCP, use DTLS for UDP
Related terms: DTLS, HTTPS, Certificate, Encryption
Synonyms: SSL/TLS, secure sockets
10.9.8 Token
Definition: A digital credential used for authentication or authorization, typically a string containing encoded information about identity and permissions with expiration time.
In simple terms: A digital key card - proves who you are and what you’re allowed to do, like a badge that gets you through certain doors for a limited time.
Common confusions:
- Access tokens vs. refresh tokens serve different purposes
- JWT (JSON Web Token) is one common token format
Related terms: Authentication, OAuth, Authorization
Synonyms: access token, bearer token, JWT
10.9.9 Topic
Definition: A named channel or subject in publish-subscribe messaging systems that publishers send messages to and subscribers receive messages from, enabling message routing.
In simple terms: A message address or category - like a TV channel number, publishers broadcast to a topic and anyone tuned to that topic receives the messages.
Common confusions:
- Topic hierarchy (sensors/temperature/room1) enables organized message routing
- Topics are usually strings, not queues (messages aren’t stored by default)
Related terms: Publisher, Subscriber, Subscription, MQTT
Synonyms: channel, subject, message topic
10.9.10 TSDB (Time Series Database)
Definition: A database optimized for storing, querying, and analyzing time-stamped data, featuring efficient compression, time-based indexing, and specialized query functions.
In simple terms: A database built for sensor data - designed to handle high-volume time-stamped measurements efficiently, with features such as retention policies, compression, downsampling, and time-window queries.
Common confusions:
- TSDB vs. relational database - TSDBs optimize for time-based writes and queries
- Examples: InfluxDB, TimescaleDB, Prometheus, QuestDB
Related terms: Time Series, InfluxDB, TimescaleDB
Synonyms: time series database
This section:
10.10 U
This section: U
10.10.1 UART (Universal Asynchronous Receiver/Transmitter)
Definition: A hardware communication protocol for asynchronous serial communication between devices, using two wires (TX and RX) without requiring a shared clock signal.
In simple terms: Basic serial communication - the simplest way for two devices to talk to each other over wires, like an old-fashioned telegraph system for digital data.
Common confusions:
- UART vs. I2C/SPI - UART is point-to-point and asynchronous, I2C/SPI support multiple devices
- Baud rate needs to match between sender and receiver
Synonyms: serial port, RS-232 (related standard)
10.11 Continue to the Next Part
This section: Continue to the Next Part — Carry this evidence into IoT Glossary: Terms From W Through Z, which begins with W.
Carry this evidence into IoT Glossary: Terms From W Through Z, which begins with W.
Find help
3 reviewed answers.
Where should I start in a module?
Open the module page from the sidebar to see its chapters in order. Use the module map to return to a topic you need.
Modules and pathsReviewed
What can I try when a project does not work?
Check the symptom, then work through the diagnostic steps. Keep the error message and the smallest example that reproduces it.
When you are stuckReviewed
How do interactive examples work?
Use the interactive guide to check how examples and simulations work before changing your project.
Interactive examples guideReviewed