Can I use It's for it has?

[shortylickens]

Or is it only a contraction for It Is?

 

[herrjimbo]

Yes, although it is frowned upon here in the states, according to dictionary.com.

Overseas, such as in England, it is appropriate.

 

[IBMJunkman]

http://www.its-not-its.info

 

[Paladin3]

In casual writing it's a go.

In formal writing leave out all contractions.

 

[lxskllr]

It has big tires
It's big tires

#2 is incorrect

 

[gorobei]

it's been a rough day for grammar.

 

[Mayne]

 

[sandorski]

It's been, one week since you looked at me....

 

[Jeff7]

I'd've been ok with it.

 

[GagHalfrunt]

Or is it only a contraction for It Is?

Depends on the situation. In business writing or school papers, I'd avoid it. For posting here, Facebook or tweets, you can use pretty much anything up to and including Klingon pig latin and it's fine. Anything in between, use your best judgement.