Do traders buy on the bid?

Excuse me, could you clarify something for me? In the world of trading, specifically in the context of cryptocurrencies and financial markets, I've heard the term "buying on the bid" mentioned quite often. Now, I'm a bit confused about its exact meaning. Do traders actually buy assets at the bid price? Or is there more nuance to it? I'd appreciate it if you could elaborate on this concept and explain how it applies in real-world trading scenarios. Thank you in advance for shedding some light on this matter.