| Typical 4K streaming data use | Approximately 7 GB per hour |
| Latency threshold for noticeable call delay | Above 150-200 ms |
| Packet loss that affects call quality | Above 1-2% |
| Bits per byte | 8 bits = 1 byte |
| Jitter level affecting audio quality | Above roughly 30 ms |
Why this glossary exists
Shopping for an internet plan or calling your ISP about a slow connection puts you in front of terms like "contention ratio," "latency," and "burst speed" with no plain-English translation nearby. Providers use these terms precisely because most customers won't push back on what they don't understand.
This reference decodes the terms you'll actually encounter, whether you're comparing plans, reading a service agreement, or running a speed test. For a related look at how chip specs use similarly dense language, see how processor cores and clock speeds are explained.
Bandwidth
The maximum amount of data that can pass through a connection in a given time, usually expressed in Mbps or Gbps. Think of it as the width of a pipe: more bandwidth means more data can flow simultaneously, but it does not guarantee that data will arrive quickly.
Latency
The time, in milliseconds, for a data packet to travel from your device to a server and return. Lower is better. High latency makes real-time communication feel delayed even when download speeds are fast.
Contention ratio
The number of subscribers sharing the same upstream bandwidth connection to the ISP. A high contention ratio can reduce real-world speeds during busy periods even if the advertised speed is high.
Data cap
A monthly limit on the total amount of data you can transfer before your ISP charges extra fees or reduces your speed. Caps are measured in gigabytes or terabytes.
Throttling
A deliberate reduction in connection speed applied by the ISP. Throttling can occur after a data cap is reached, during network congestion, or for specific traffic types.
Jitter
The inconsistency in latency over time. High jitter causes choppy audio and video during calls because data packets arrive at irregular intervals rather than a steady stream.
Packet loss
The percentage of data packets that fail to reach their destination. Even small amounts of packet loss can degrade video calls, gaming, and other real-time applications noticeably.
Burst speed
A short-term speed increase above the plan's advertised rate, usually lasting only a few seconds at the start of a transfer. Sustained download performance is a more reliable indicator of real-world experience.
Speed and bandwidth terms
These are the numbers ISPs advertise most prominently, and the ones most likely to mislead you if read without context.
| Typical 4K streaming data use | Approximately 7 GB per hour |
| Latency threshold for noticeable call delay | Above 150-200 ms |
| Packet loss that affects call quality | Above 1-2% |
| Bits per byte | 8 bits = 1 byte |
| Jitter level affecting audio quality | Above roughly 30 ms |
Download vs. upload speed
Download speed measures how fast data travels from the internet to your device; upload speed measures the reverse. Most residential plans are asymmetric, meaning download speeds are much higher than upload speeds. If you video-call, stream to a platform, or back up files remotely, upload speed matters more than the headline download number suggests.
Mbps and Gbps
Mbps stands for megabits per second; Gbps stands for gigabits per second. One gigabit equals 1,000 megabits. Note that internet speeds are measured in bits, while file sizes are measured in bytes (one byte equals eight bits). A 100 Mbps connection downloads a 1 GB file in roughly 80 seconds under ideal conditions.
Burst speed
Some plans allow short bursts above the advertised speed for a few seconds at the start of a download. Providers use burst speed to make connections feel more responsive. Sustained performance, not the burst, is what affects large downloads or long video streams.
Latency, jitter, and packet loss
Speed is only one dimension of connection quality. These three terms describe how reliably and quickly data travels between your device and a remote server.
Latency
Latency is the time, measured in milliseconds (ms), for a data packet to travel from your device to a server and back. Low latency matters most for real-time applications: video calls, online gaming, and voice calls over the internet. A 20 ms latency is hard to notice; 200 ms makes conversation feel awkward.
Jitter
Jitter is the variation in latency over time. Even if your average latency is low, high jitter causes choppy audio and stuttering video because packets arrive at uneven intervals. Jitter above roughly 30 ms tends to affect call quality noticeably.
Packet loss
Internet data travels in small units called packets. Packet loss is the percentage of those packets that never arrive. Any packet loss above about 1-2% can degrade video calls and gaming. When you run a speed test and results look worse than expected, packet loss is often worth checking. For context on interpreting those results, see common myths about internet speed tests.
Plan structure and policy terms
These terms appear in service agreements and billing documents. Understanding them prevents surprises on your bill or during peak hours.
Data cap
A data cap is a monthly limit on total data transferred. Exceeding it can trigger extra charges, throttled speeds, or both, depending on your provider's policy. Caps are measured in gigabytes (GB) or terabytes (TB). Streaming 4K video uses roughly 7 GB per hour, which can erode a 1 TB cap faster than most households expect.
Throttling
Throttling is the deliberate reduction of your connection speed by the provider. It can happen after you exceed a data cap, during network congestion, or for specific types of traffic. Some plans advertise unlimited data but include throttling language in the fine print after a certain usage threshold.
Contention ratio
Your connection to the ISP is shared with neighboring subscribers. The contention ratio describes how many users share that capacity. A ratio of 50:1 means up to 50 households share the same upstream bandwidth. Higher ratios often produce slower speeds during evenings when demand peaks.
IPv4 and IPv6
Every device on the internet has a numerical address. IPv4 addresses are the older format (e.g., 192.168.1.1); IPv6 is the newer, much larger address space designed to accommodate the growing number of connected devices. Most connections use both protocols simultaneously through a method called dual-stack. This rarely affects everyday browsing but can matter when configuring home network equipment or VPN software.
For a parallel look at how port and cable standards use similarly layered naming conventions, see USB standards and cable speeds explained.