How do you know when your in love?

Dunno.

I think it's probably when you will do anything to make them happy, unconditionally, selflessly. That's true love.

I disagree to that being love. I do that with my g/f but I don't love her yet. Its a feeling/emotion thats uncontrollable and unexplainable.

for me it was when:
Every small thing whether it was a song on a radio to an item in a shop reminded me of her.
I felt hollow inside every moment spent without her but felt complete when i was with her
I thought about her smile from time to time during the day and every time i did i felt great inside
Even the smallest of things about her made me miss her.

so i guess it'll probably be similar things to that which may indicate your in love....

Being in love is great. You'll definitely know the feeling or feelings. Basically you won't be able to get this person outta your mind at all so you'll be thinking of them the whole day which is great, cos it means that your on a constant high and happy and jumping about the place

You'll definitely definitely know when the time comes and you are attacked by the lurrrrve bug

Yeah I agree with what the above says. If you can try to explain it, I would say -
Its when life starts feeling beautiful and you have a greater purpose for waking up everyday.
It feels as though all your dreams have come true and Mainly theres only one name in your head at all times.
With me I even tollerated the things I hate most for her and I was happy doing it.

Exactly! It's like when you wake up and LITERALLY the first thing you think of is his/her name. And when you go to sleep at night you just imagine their face or their name or something while you slowly drift off into sleepland....hehe

Anyway its just a general cheery sensation that life can't touch you because you actually have it all. I remember feeling at the time I was in love (not now lol) that I wouldn't even swap this guy I love for any amount of money millions of billions thats how happy I was with life!