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A cafe owner pays for '200 Mbps' but Zoom still freezes at lunch. The ISP says 'speed is fine.' Both are right: the pipe is 200 Mbps, but 40 customers share it and the WiFi adds 80 ms delay. Speed alone never tells the full story.
Everything on a network is bits: 0s and 1s. 8 bits = 1 byte. ISPs sell you bits per second (Mbps). Your browser shows bytes (MB). Divide by 8 to translate. 100 Mbps internet = about 12.5 MB/s download max. That confusion causes half of 'slow internet' tickets.
| Term | What it is | Example |
|---|---|---|
| Bandwidth | Size of the pipe, what you pay for | 100 Mbps fiber |
| Throughput | What you actually get right now | 62 Mbps at lunch |
| Latency | Delay, how long one bit takes | 8 ms home, 120 ms to another continent |
| Jitter | Latency changing | Voice cracks when jitter > 30 ms |
| Loss | Bits that never arrive | >1% loss = video freezes |
Analogy: bandwidth is lanes on a highway, latency is speed limit, throughput is actual cars per hour at rush hour, loss is cars that fall off a bridge.
Under 1 ms = same room/rack. Home WiFi is usually 2-10 ms. To your ISP 5-20 ms. Across the ocean 100-200 ms. If ping to your router is already 200 ms, the problem is inside your house, not the internet.
You can now read a speedtest like an engineer. Next: what actually happens when you open google.com — DNS, IP and MAC in plain English.
Finish the lesson once you have worked through the material. This awards ★ 40 XP.