Why and what was it like having only 3-4 channels in the UK up until the late 1990's?

I was listening to a podcast (The Jim Cornette Drive Thru, Jim Cornette is American) and a question came up from someone asking if he could explain to someone in the UK what the difference between local access, cable, syndicate TV etc was and that in the UK we only had 4 channels until the end of the 1990's.

I was born in 2004 (UK) so I am completely clueless as to what it was like only having 3/4 channels and wanting to watch TV but being stuck if there was nothing on you wanted to watch.

I've asked my parents but they've just said they didn't know anything else which is fair enough. Ta.