Download speed is actually talking about your bandwidth, specifically your downstream.
This is the part of your connection that receives data from the internet.
Your download speed is relevant for almost all online activity as everything you see on the internet has to be sent to you through the downstream.
Instead of making data move faster, a higher bandwidth (what is listed as higher ‘download speed’) means more data can move through your broadband connection at the same time.
The download speed is the maximum amount of data that can be sent to your connection, so a 17Mbps ‘speed’ means you can receive a maximum of 17 megabits of data every second.
Similarly, if you have fibre broadband capable of ‘up to 76Mbps’, that means you can receive a maximum of 76 megabits of data every second.
A higher download speed increases the maximum potential speed of your home broadband.