What is the difference between download and upload speed?

The answer

Download speed is how fast data reaches your device from the internet, and upload speed is how fast data leaves your device. Browsing, streaming and receiving files rely mainly on download, while video calls, cloud backups, sending large files and online cameras rely on upload. Many connections offer much lower upload than download, and some plans are symmetrical. If a plan page lists only one number, ask for the other, and ask for both figures in writing before you decide.