system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why is finding water on other planets one of the most important things for us to look for in the case that there is life there?

I get why it could be important but nothing else seems to matter when looking for life.
gpt
So life needs chemistry to take place to exist.

For chemistry to take place chemicals have to come into contact with each other.  A chemical sitting on one rock and another on another rock won't react with each other.

So they need to mix in something.

This best place for chemicals to mix is in a liquid.

Of all liquids water is the best for this to happen in since water can dissolve more chemicals in it than any other liquid.

Hence, they look for water.