Well, most asexuals can experience forms of attraction that are not sexual. Like really liking someone's style, the shape of their face, the way they do their hair, the way they carry themselves, etc. That's what draws people in when there isn't that sexual "spark." Then there's emotional/romantic attraction, which usually comes after getting to know someone a little, and what most people in general experience in relationships or even crushes. Then if you want to get really complicated, a portion of asexuals are totally okay with (or even enjoy) having sex, usually if they're in a committed relationship with the person, which is the category I fall into.