How many balls can you get before you walk?

I'm curious to know, in the context of baseball or a similar sport, how many balls a batter can receive before they are called out on a walk? Is there a specific number of pitches that a batter must see before being awarded a walk, or does it depend on the situation and the umpire's discretion? I understand that a walk occurs when the batter reaches base without a hit, but I'm interested in the specifics of how that is determined. Can you provide a clear and concise explanation of the rules surrounding walks in baseball?