THE BUSES are self-explanatory. They have buses where you’re from. You know how buses work. The light-rail system, the MAX (it stands for Metropolitan Area Express and yes, that is a totally forced acronym) is also fairly easy to understand. But! There are also these other, smaller trains....
That is the streetcar. The streetcar is not the MAX. The MAX is light rail. Think of the streetcar as lighter rail. The MAX is an interurban system that serves the whole metro area and can get up to highway speeds when outside of the urban core. The streetcar, on the other hand, never leaves the central part of Portland, stays on the... well, street... and is routinely outpaced by bicyclists.
Until the 1950s, Portland had a streetcar system that knit together most of the now-established neighborhoods. Our modern streetcar is a sort of echo of that old transit system, and has been in operation since 2001. Unlike the MAX and bus system, the streetcar is not administered by TriMet. It’s a project of the City of Portland itself.
Plenty of Portlanders dismiss the streetcar as slow and superfluous, but people actually do use it, and it’s been a boon to development. That’s a big part of why the thing exists at all. Sure, it’s transit... but it’s also a symbol of a particular kind of urbanism. By having the streetcar, we have become the sort of city that has a streetcar—and therefore embody all the nebulously progressive stuff this entails.
And yes, you do need fare to ride it. It’s two bucks, or valid TriMet fare also works. You could conceivably jump on and not get caught by fare inspectors. But if you do, just give them two dollars. It’s the cheapest ride in town.