Let's face it, folks: breasts are pretty great. Almost everyone who is sexually attracted to women has a fondness for them, and plenty of other people besides can enjoy looking at them or playing with them. For those of us who have our own they're often a big part of the way we dress and the way we dress up, and people who think of their breasts as being one of their best physical features can have a lot of fun with dresses, corsets and plunge bras designed to show them off.
There's more than one way of getting your breasts involved in your fetish life, too. If you have a breast fetish, breast worship is a common practice amongst people who enjoy submitting to women, while those who get off on dominating them might want to indulge in a little tit torture or breast bondage. For most people they're a major erogenous zone, making them a great place to bite, suck, spank and squeeze. Just make sure you have the full informed consent of your partner before you get down to anything!
People bind their breasts for all kinds of reasons. For some people, it's a part of helping themselves to look the way they feel they most want to look; this might be an aesthetic choice, or a part of someone's gender expression. For others, it's like a costume - a way of being someone else for a while, or of taking on a certain role. Genderqueer and non-binary folks might bind in some situations but not others, or on days when they feel their gender expression will benefit from it. Binding isn't usually overtly sexual, though many people who bind find it more comfortable to remain bound during a sexual encounter.
While the breasts aren't primarily a sexual organ, they're certainly popular as a secondary sexual feature, and there are plenty of kinks and fetishes that focus on breast stimulation. Many people enjoy breast bondage, which can create a certain look and heighten sensation; nipple clamps are popular tools in nipple play, and some even vibrate or come with weights for a variety of sensations. If impact play is your thing, the breasts are a great place for it; particularly if you enjoy marks and bruises, as they're prone to colouring nicely! Just be careful and, as always, do your research.