See also miniseries, micro-series, summer series, Masterpiece Mystery!, and limited series I want to see
This is a concept I've been aware of since at least as far back as 1991, but by the time I started writing reviews online (about a decade later), I suppose I'd seen so few "limited series" that I just decided to lump them in with miniseries. (And indeed, some limited series are even called miniseries by the network that airs them.) This includes both American programs, and British shows that would be called serials (though that term can have other meanings related to TV shows, so it's one I usually prefer to avoid). Basically, the way a limited series differs from a miniseries, at least to my way of thinking, is that it airs on a weekly basis, like a regular series, whereas miniseries usually air two or more installments within a single week* (in rare cases on a single day, which can lead to some confusion as to whether they're really miniseries or just extra-long TV movies). A lesser distinction is the actual length of episodes. Those of miniseries can be of any length, but most commonly each installment is two hours long, whereas episodes of a limited series are more often an hour (or half hour). (But of course, they can be longer, which is why I call this a "lesser distinction"; there are too many exceptions to call it a rule.) But I suppose the main thing that qualifies a series as "limited" is that it was intended from the start to air for a single season, consisting of fewer episodes than a normal (American) season. (British serials usually have fewer episodes than American limited series, because their regular seasons are usually shorter than American regular seasons.) Of course, there are also some shows that are intended from the start to last a specific number of seasons (e.g., Babylon 5 was always meant to be five seasons and Avatar: The Last Airbender was always meant to be three), so in a sense you could think of such shows as "limited," considering most series, even ones that get cancelled after a single episode, probably don't have a specific plan for exactly how long the writers and producers intend them to run. But for the purposes of this section, I'm going to try to chiefly focus on shows that are intended to run for a single (shorter than average) season.
However, one problem with calling something a limited series is that even if they are initially announced as such by the network, if they prove successful enough, they can be renewed for a second or more seasons. This is something that often bothers me, because I tend to feel it compromises the original intentions of the writers (though I don't expect the writers themselves would necessarily agree with me). The biggest problem with that is that they could have a specific plan in mind for how to wrap up the story at the end of a specific number of episodes, but if they get a second season, then they probably won't wrap it up at the end of the first season, which requires rewrites and annoying cliffhangers, and makes me feel like I've wasted my time watching the first season. (There are often limited series that I find worthwhile to watch for a single, short season, but which I don't like enough to bother watching a second season, which means even if the show ultimately has a satisfying conclusion, I won't see it. Which produces the same feeling as when a regular series gets cancelled before the writers have a chance to resolve all the plotlines.) Of course, it doesn't always bother me. For example, Northern Exposure started as a limited summer series, before becoming one of my favorite regular series ever. And The Legend of Korra was originally intended as a limited series, before being renewed for more seasons. And I'm sure there must be other examples of shows I'm glad got extended. (I should also mention that, while I mainly think of limited series as having a plan for a single, complete story arc with a definite ending, there are some series I include here, particularly summer series, that are more episodic than serial, and don't have a definite plan for anything like a story resolution, even though they're not expected to last beyond a certain number of episodes.)
So, anyway... I eventually decided to move some of my reviews from the miniseries section into regular series categories, while leaving others under miniseries. And there are some things it never occurred to me to think of as limited series or miniseries, in the first place (especially some British serials). I've gone back and forth on whether or not to start a limited series section, but I finally decided to do so. So, I'll be moving things in here from various other sections. Although it's possible there will be some limited series I leave in other sections, simply because I have no idea whether they were specifically intended as limited series; it could be that they were intended as regular series, but got cancelled or failed to get renewed. So I tend to err on the side of caution.
*This may seem an arbitrary distinction, given that the schedule on which a show airs probably bears little or no relation to the schedule on which it was filmed, and a network could just as easily have aired some things that I consider miniseries on a weekly basis for a few weeks and some things that I consider limited series on a daily basis for perhaps a single week. It really doesn't matter that that's not the way they aired it... but since I'm set in my ways, and because regardless of whether the scheduling is arbitrary... well, it is what it is.