What does it mean when you're demi? I never fully understood.

It means that you only feel sexual attraction once you've formed an emotional bond to a person. For someone who is demi, an emotional bond has to be formed, before any kind of sexual attraction can occur. That doesn't mean it will definitely occur, just like people who aren't demi aren't attracted to every one they meet, but an emotional connection is a requirement.

Demi can apply to a lot of things. It normally means you are partially something or inbetween two things. Personally i am a part of the demigender group (demiflux) and the demisexual group. Demigender means you are partly one gender and partly another. One tends to be stronger then the other. Demiflux means part of your gender stays the same while another part fluctuates in intensity. Demisexual means you dont tend to experiance attraction to someone till you know their personality. Its kinda inbetween sexual and asexual. If someone says they are demi it really depends on whether they are talking about their gender, romantic attraction or sexual attraction etc.

Being demisexual means having sexual desires only about people you have feelings for. For demi people, there is no sexual attraction without romantic attraction. Of course, demi people can be attracted to the same gender, or the other, or both... But the constant factor is that sexual attraction is only there when romantic feelings are there.