The internet was a new and exciting place in the 90s. It was a time when people were just starting to get used to the idea of chatting with strangers online. The chat rooms were a place where people could meet and talk about anything they wanted.
Chat rooms were also a place where people could find friends, or even partners, without having to leave their homes. They were also an easy way for people to find out about new things happening in their area or around the world.
ASL (Age?, sex?, location?) was used to deduce a little basic information about how it was you were talking to.