Where do you buy chain swap?

Excuse me, I'm a bit new to the world of cryptocurrency and I've heard about this thing called chain swap. Could you please tell me where exactly can I buy it? I've been looking around online but I'm not really sure where to start. Is there a specific exchange or platform that I should be using? And if so, could you also recommend any safety precautions I should take when making a purchase? Thank you so much for your help!