"Suburb" is usually the bit of America where every house is made from the same McMansion catalog, all roads are paved and there's not a shop, store or office in sight.

Everyone leaves at the same time like clockwork to go to work with their immense SUV, alone of course, driving through a congested interstate to the nearest city to their office. Then the spouse leaves on their SUV to take the kids to school, queueing to drop them off.

If someone sees anyone walking in the evening or at night, they call the cops and the walker is arrested first, then investigated later. The unlucky ones get shot.

I can't tell if this is satire or not, but it sounds absolutely horrific and I have no idea why anyone would want to live like that. I guess different people just have different tastes.

"Suburb" covers a lot of ground. There's the classical US cul-de-sac development of course. But people also use the term to encompass small cities and the periphery of larger cities that are mostly spread-out single family homes often generally lacking the ability to easily walk to stores, etc. Or largely exurban towns that may have a center but with homes often spread over a number of acres. (Which are still often considered urban by the US Census because they're basically within an hour or so of a larger city.)

wikipedia struggles a bit with the definition, but the pictures at the right show very clearly how large the range of what at least sometimes is called a "suburb" is: https://en.wikipedia.org/wiki/Suburb

But for discussions like this you probably can assume that people mean the less-dense, residential-only types

Yes, people think about characteristics like needing a car, mostly segregated (strip malls, industrial parks) commercial development, primarily single family homes, etc. but not truly rural (although that's a matter of degree). Whether or not it's actually a suburb of a city, an outlying town, or part of an outlying smaller city.