You think about them often.You try to run into them so that you can smile or say hello. You ask other people about person's dating/marital status. You get a funny feeling in your stomach. You make up reasons to talk about them and see them. Every time you see them, you stare until they look, and then you look away. You can't stop thinking about them. You get a weird feeling often described as butterflies in your stomach. You get nervous around them. You can't help staring at them. You blush or start sweating (even a little) when they ask you something or compliment you. You blush when you help them with something. In most cases when you have a crush, you tend to look at his/her face a LOT. Usually the face is what attracts you to that person. You know if every time you look at them you get a weird feeling go through you. You get extremely clumsy! You stare at them, hoping they won't see you. You get all giddy. And you get so nervous, you're speechless. You think about them almost all the time. You tend to look for them everywhere. Everything somehow reminds you of him/her. You get all energetic when you see him/her around or you get really nervous and self-conscious. You can't talk to him/her properly. When you're in the same room with them, you tend to glance at them a lot...and when they look at you, you get this urge to smile. You're usually happy when their around. When you walk into a room, they're the first person you look for. You think of them a LOT, even in the middle of something big or important. You miss them even when you just saw them a few minutes ago. Sometimes (depending on how good friends you are with the person), you get nervous around them or when you know you're going to see them that day, you get butterflies in your stomach. And (shocker) you look forward to going to school on Mondays just to see them! (Only of course if you actually go to their school or go to school at all depending on the age) These are all things that I do when I have a huge crush on someone. You suddenly can keep a 'good' eye contact, you feel like can't take your eyes off when talking to them. You feel energetic and happier, even when that means you have to go to office during weekend or holidays. You are curious abut who gave them whatever-cards that they put on their desk, curious abut who they have a chat with in messenger, curious abut who they're talking to on phone. You start recognize the their ring tone changes, their fragrance, their way to talk. You look forward to seeing them and daydream (and dream over night) about them. It's a huge and exciting experience. You try to become friends with one of there friends, so that will give you a reason to go up and talk with them. and then after that he/she starts talking to you and what not. The answer is in your eyes .When the thought of that person makes you feel good about yourself, when you encourage interaction with that person to increase the feel-goods you get from the interaction. Also, your pupils will dilate whenever you think of anything exciting, especially romantically so. You always want to be around them, no matter what it takes. You tend to be annoying to them, so you can get their attention. Sometimes you won't stop bothering them even if you get in trouble for bothering them. You just feel happier around them.