How do computers download data, and discern 1's from 0's

Question

From my understanding, when a computer downloads something from the internet, a stream of bytes is sent via electrical signals, what I am wondering is how this data is parsed? My first thought was maybe it's based off of some sort of clock, like if your download speed was 1 bps, then it knows that the state of electricity in that 8th of a second represents a bit of 1 or 0, but what if the rate slows to 0.5bps, then every 1/4 second would represent a bit. So with this process:

10010110

would be seen as:

11000011 00111100

if this change in rate happened, and as we know, the rate of download changes constantly, so my question is as follows, how does the computer actually interpret the 1's and 0's in the stream? Or is my understanding of a stream incorrect?