It can change over time. My personal experience is that my sexuality has stayed pretty much the same, but the way I think about it has changed over time. So that coming out as bisexual meant to me reconciling all the different pieces of my sexuality. Bisexuals are equally attracted to men and women. The reality is some are.
Many people are more attracted to men or more attracted to women.
I consider myself bi-curious. But the part of that, for me, is that I know that I am not just a one-sexed individual. I consider myself a sexual being. We'll talk more about that. I tend to fall between five and six.