Is it 18살이고 or 18살이에요 ?

Also in general, how would you say your age when introducing yourself?
Many websites are saying different things, so I’m a bit confused😅

Thanks!

Question

Is it 18살이고 or 18살이에요 ?

Also in general, how would you say your age when introducing yourself? 
Many websites are saying different things, so I’m a bit confused😅

Thanks!

Answer

I'm 18 years old - 저는 18살이에요.
I'm 18 years old and (...) - 저는 18살이고 (...)

이다 - verb to be
이에요 - verb to be in present tense
고 - and (used for verbs)