I am an American who is 18 years old. If I visit another country where the drinking age is 18 and above am I allowed to drink alcohal?

You follow the laws of your host country you are in.

Since you can't figure that out, you are too stupid to drink.

You certainly can. The law that applies is the law of the country you are in,

It would be wise to NEVER EVEN START
Drinking alcohol. It is Addictive as drugs
And will ruin you health and destroy all
Your relationships. Most divorces start
With some form of addiction and the
Problems created are just to big to
Work out so the girl leaves you with
A huge debt and other problems. Like
Paying child support the rest of your life.
Wise up or you will suffer the rest of your
Life due to your stupid choices.

Inability to spell " alcohol " combined with your depression tells me you shouldn't drink it anywhere.
https://answers.yahoo.com/question/index?qid=20170905155210AA6l7SW

Yes. That's why Europe is full of drunk American teenagers.

Local laws always apply. Unless you're a Muslim in which case the country you're visiting is expected to observe Islamic law.

Of course.