During the TLS handshake, there are random bytes sent from the server to the client and random bytes sent from the client to the server.
Since these bytes are sent in clear text, what is the relevance of them being random? I thought randomness was mostly about lowering the likelihood that these numbers could be guessed. If they are passed around in clear text; whats the importance of the randomness?
Also, what exactly are these random bytes used for?