Internet Speed Terms Explained: Ping, Jitter, Bandwidth & More (Glossary)
ITSpeedTest.net ·
Speed tests and broadband plans are full of jargon — Mbps, ping, jitter, bufferbloat, latency, throughput. This glossary explains every common internet speed term in plain English, a sentence or two each, with links to our deeper guides where you want more. Bookmark it, or jump straight to a term, and run our free speed test whenever you want to see these numbers for your own connection.
What is download speed?
How fast data travels from the internet to you, measured in megabits per second (Mbps). It powers streaming, browsing and downloads, and it's the headline figure most plans advertise. See what counts as a good download speed or measure yours with our download speed test.
What is upload speed?
How fast data travels from you to the internet — used for video calls, cloud backups, online gaming and posting. On most home plans it's much lower than download. Check yours with our upload speed test.
What is bandwidth?
The maximum amount of data your connection can carry at once, usually quoted in Mbps. Think of it as the width of the pipe: more bandwidth means more devices and activities can run together without slowing each other down.
What is throughput?
The actual data rate you achieve in practice, which is often lower than your plan's headline bandwidth because of Wi-Fi, congestion or older hardware. A speed test measures throughput — your real-world speed right now.
What does Mbps (megabits per second) mean?
The standard unit of internet speed: millions of bits transferred per second. A "100 Mbps" plan moves up to 100 million bits each second. Don't confuse it with MB/s — see below.
What is the difference between MB/s (megabytes) and Mbps (megabits)?
There are 8 bits in a byte, so speeds in Mbps are eight times bigger than the MB/s your browser shows when downloading. To convert, divide by 8: 100 Mbps equals about 12.5 MB/s. Note the capital B (bytes) versus lowercase b (bits). Full explanation in how to read your speed test results.
What is ping?
The round-trip delay, in milliseconds (ms), before data starts moving between you and a server. Lower is better — under 50 ms feels responsive. It matters more than raw speed for gaming and video calls. Test it with our ping test.
What is latency?
Another word for the delay in your connection — ping is how we measure it. Low latency means your connection reacts quickly, which is what fast-paced games and live calls depend on. More in our gaming speed guide.
What is jitter?
How much your ping varies from one moment to the next. A steady ping feels smooth; high jitter causes stuttering calls and laggy games even when the average looks fine. Aim for under 5 ms.
What is packet loss?
The percentage of data that's sent but never arrives and has to be resent. Your target is 0%. Even small amounts cause glitching video, missed game actions and disconnects, and it usually points to Wi-Fi or a line fault.
What is bufferbloat?
A latency spike that happens when a big upload or download fills your router's buffers, sending your ping soaring under load. It's a hidden cause of lag — fixed with Smart Queue Management (SQM) or QoS, not a faster plan. See our gaming guide.
What is a router?
The device that shares your internet connection with all your gadgets, usually over Wi-Fi. Its placement, age and settings have a huge effect on your real-world speed — see how to increase your internet speed.
What is a modem?
The device that connects your home to your provider's network. It's often combined with the router in a single box. A failing modem can cause slowdowns that no setting will fix.
What is Wi-Fi (2.4 GHz vs 5 GHz)?
The wireless link between your devices and your router. Most routers offer two bands: 2.4 GHz reaches further but is slower and more congested, while 5 GHz is much faster over shorter distances. Choosing 5 GHz near the router is a quick speed win.
What is Ethernet?
A wired connection between a device and your router. It's faster, lower-latency and far more stable than Wi-Fi, making it the best choice for gaming PCs, consoles and anything that needs a reliable connection.
What is mesh Wi-Fi?
A system of units that blanket your whole home in a single strong network, handing devices off seamlessly as you move around. It's the proper fix for dead zones — far better than a basic extender, which often halves speed.
What is DNS?
The "phone book" of the internet, translating web addresses into the connections behind them. Switching to a fast public DNS (such as 1.1.1.1) can make pages feel quicker to load without changing your raw speed.
What are QoS and SQM?
Router features that prioritise important traffic. Quality of Service (QoS) puts video calls and gaming ahead of background downloads; Smart Queue Management (SQM) tames the latency spikes known as bufferbloat. Both live in your router's settings.
What is an ISP (internet service provider)?
The company that supplies your internet connection. Your ISP sets your plan's speed and may throttle certain traffic or slow you after a data cap. If a wired test is far below your plan, your ISP is who to contact.
What is throttling?
When your provider deliberately slows specific traffic — like streaming or large downloads — or your whole connection after a data cap. If some activities are reliably slow while others are fine, throttling may be the cause. See why your internet is slow.
What are fibre, cable, DSL and satellite connections?
The technologies that deliver your internet. Full fibre is fastest, usually symmetrical and lowest-latency; cable is fast on download but lower on upload; DSL runs over older copper lines; satellite reaches anywhere but has the highest latency. Your connection type sets the ceiling on what's possible.
What is the difference between symmetrical and asymmetrical connections?
An asymmetrical connection gives you far more download speed than upload — normal for most home plans. A symmetrical connection, typical of full fibre, gives equal speed in both directions, which is ideal for video calls, uploading and remote work.