What exactly is “flirting” ~vs~ being “Nice”?

Hello Folks!

I was wondering how can you really tell if someone is flirting with you?

What if you are wrong? What are the signs that they want to see you in your panties? What is it exactly that a man says to a woman to give her a hint that he’s totally interested?

Nice shoes? You smell good, what are you wearing? So, do you come here often? I hope to see you again…You work out huh?

I am asking because a friend of mine was on the phone with me when this guy asked was his jacket too big? Ok, I engaged and said a little but it looks fine since guys shouldn’t wear tight clothes. So, my friend shouts “He’s flirting with you!”

That was flirting? Hmmm?