So I've got this problem and I searched the list of threads here for a similar one but couldn't find or see any. I don't know how to put this so I'm just gonna do it straight forward.
How do I know if I like a person? And how do I differentiate between "I-like-you-let's-hang-out" and "I-want-relationship-with-you"? Lot's of thank you's if you can help me.

How do you know if you like someone? Assuming you're a girl, I'm not sure. It's easier for men like me to figure out because if we like a girl we usually get a boner. I'm not sure what happens when women like someone. Get wet I suppose...? idk

Err... wasn't expecting that. But wouldn't that be just sexual attraction? I was asking about it feelings wise. And yes, I am a girl.

[Disclaimer: You may or may not |0| at the following corny things I'm going to say.]

Alright. So. How does a girl know when she likes someone? If you're going for sexual attraction, you get wet. However, sexual attraction is different from the "I-want-a-relationship-with-you" type of deal (for most people). Just because a guy gets a boner watching girls in short skirts pass by doesn't mean that that guy wants to be in a relationship with those girls - it means he wants to do the sex. Which is not just what you're looking for, as far as I can tell.

Generally, an easy way to tell if you like someone is how embarrassed you are around them. Do you blush? Do you get goose bumps? Do you feel really awkward talking to or walking past them? It all depends on the girl, though. Some people have different ways of telling. Some people rely on their conscious thoughts--how good looking they are, their distinct personality, et cetera--while others rely on often unconscious feelings like what I said above.

If you just want to hang out with them, you're not going to feel uncomfortable or get goosebumps unless you're super, super, suuuper shy. If you're not suuuper shy and you feel that way, chances are: you like them.

Pretty sure its not something we can tell you, but something you would have to figure out on your own. Everyones different in what qualifies as liking someone. For king its getting a raging boner, and for sama its feeling all shy n tingly when theyre around.

I think this matter is hard to explain and different for everyone, but for me, it's kind of like what Barabisama said. You feel differently around them than you do with your other friends. Even just seeing them walk by might make you nervous or really happy.
I think if you begin to like someone, you'll know it and you won't really need someone to tell you. You'll feel a certain way and know that you really like them. If you never feel this way towards anyone and you can't understand it, then perhaps you are asexual. Or maybe you just haven't met anyone that you really like yet.
Hopefully one of these comments has helped you, but it really is tough to explain.

What'll you do if you realize you do like someone? If you liked someone, would it be because of their looks, or personality, or of your history of knowing that someone?

Actually, that's what I want to find out. When I'm around a friend of mine, I feel slightly shy but we're friendly with each other most of the times. Does that say anything?

Just get to know that someone more and maybe you'll figure it out for yourself :) good luck