What are healthy boundaries? What are boundaries in the first place?

Depends on the context of the boundary. In a professional relationship, e.g., there may be certain "boundaries," or social rules, that must be observed (such as avoiding topics relating to religion or politics in the workplace).

Healthy boundaries means making informed considerations when interacting with others based on balancing your needs with theirs and making an effort not to offend or overstep lines that other people have.

Boundaries are lines that you draw for yourself. Lines that you will never cross no matter what. Its okay to have certain boundaries if it is for your own good. But too much boundaries can cause a wall that will not allow you to experience much.

Boundaries are what feels comfortable for YOU.It's a matter of what makes you feel safe and secure!

Boundaries are positive limits that you express to someone in order to give a relationship a nice structure. Interaction is based on what we receive and what we give, but sometimes it's hard for us to set limits because we're afraid to mess it up or to offend the other person. Healthy boundaries delimit the area where you can feel safe, positive, energetic and ready for the game of life. There are also unhealthy ones when we become manipulative or passive-aggressive towards people, or when we push them to second-guess our thoughts without expressing them in a proper, assertive way.

Healthy boundaries are invisible rules and/or guidelines that tell people what you're willing to accept and what you're not going to accept for your own well-being. A boundary, in my opinion, shouldn't be there to protect your "ego". For example, setting a boundary that's trying to actually control someone else's behavior because of your insecurity. It's nice to feel safe but trying to have things, always, a certain way might lead one to wonder, "what is the root of what you're trying to protect yourself from?" Boundaries are for yourself and you should be: short, clear and held firmly in.