No sassy answers please, I am simply just curious and I am not an idiot.
The answer by the way is: really not that strict.
I didn't get ID'd for alcohol once but obviously I did for weed and my friend had a driving license ID and that was accepted so passport is not the only form of ID you can use!
You must be 18. And the only ID they will accept is your passport.
Some bars ask everyone for ID, others don't. The ones that ask are usually the trendy ones or in tourisy locations like Leidseplein. But if you are in a neighbourhood casual bar, the type of place old guys like to drink, they are usually less strict unless you look really young
As for smoking, they always ID everyone and you won't even get in without an ID. I was with friends in their 30s recently and everyone had to show an ID to come in, even though they were obviously over 18. Most coffee shops have a policy that they ID everyone
The legal drinking age in the Netherlands is 18. You will be asked for ID and that means showing your passport as it is the only ID you can use. While you might be allowed into bars, you will not be allowed to drink.
If your friend plans to smoke weed etc you cannot join her, and she cannot buy anything for you to have later. You will not be allowed inside the CoffeeShops and will have to find sonething else to do.
Like most cities, some bars will ask to see ID and some won't. I'm sure you won't have too much trouble. ????