The word gets used constantly. Here's what it actually means, and why it's harder than it sounds.

If you've spent any time in therapy, read a self-help book, or even had a conversation with a friend about a difficult relationship, you've heard the word "boundaries." It gets thrown around so often that it's started to lose meaning.

"Set better boundaries. You need to have boundaries. Their boundaries are all over the place."

But when people actually try to explain what a boundary is, things get fuzzy fast. Is it something you say? Something you feel? A rule you enforce? A wall you put up?

Here's a clearer way to think about it, one that's actually useful.