Whether you smoke the herb or not, coffeeshops in Amsterdam are a tourist attraction by themselves. Choose the right one and it'll be an experience you'll never forget. Choose the wrong one and you you'll probably forget that you were in Amsterdam altogether.
The experience may not be around for long should the Dutch government have its way - yes, even in the peace-loving Netherlands, an openly xenophobic and extremely conservative politician has been voted into government. This revival of right-wing popularity has resulting in conservative lawmaking, which affects even the humble coffeeshop via intrusive laws and regulations (ie. a 'Weed Pass' for Dutch citizens, extra coffeeshop licences and purchase restrictions).
Because Amsterdam is a tourist Mecca you'll see plenty of foreigh clientele at most places. For readers who prefer coffeeshops with more local patronage, this will be noted in the coffeeshop description as much as possible.
There are many different types of coffeeshops, for different kinds of people. Some look more like nightclubs, others like Tibetan monasteries (once you're stoned) and others like super-modern cafés. And in the summer, many have outside seating, sometimes near the canal.
Coffeeshops in Amsterdam have a particularly long history (Mellow Yellow was the first one in 1973), even during times of cannabis prohibition. The idea has been imitated across much of Europe, as well as the Americas, proof enough that the system works (for the 'evil' criminal gangs anyway).
Given the city's status as a major shipping hub and its maze of canals, it's not hard to imagine how drug trafficking in this city was an attractive option. Coffeeshops could easily be supplied straight from shipping containers via the many canals on small boats, and even emptied in the same manner should the authorities decide to pay a visit, before the premises had even been entered.
Today, they are mostly supplied by car, a much less romantic option. Naturally, one could dream up other ways, especially when sitting in the den of creativity that can be a coffeeshop...
After extensive wandering around (and getting lost in) Amsterdam, a list of 25 coffeeshops (of the 280 available) not to be missed during your stay is provided here. They are selected from across the city, so that you're never at any point far away from one of these exceptional Dutch institutions.