One of the really cool [1] things about television shows these days is the complexity and sheer number of storylines that they're squeezing into them. What's even cooler is that we're able to follow each of those threads, for the most part, reasonably easily. Though recaps and other assists help us keep things straight. Of course, this is not to say that the A/B storyline concept is dead [2]. That is indeed alive and well, and will continue to be the dominant narrative form on television for the foreseeable future.

If that jargon has thrown any of you, here's a quick recap. A storyline is a narrative thread "experienced by different but specific characters or sets of characters that together form a plot element or subplot in the work of fiction" [Source: Wikipedia]. Basically, a storyline is a plot (if there's only one storyline) or a sub-plot (if there are more). You can also call them story threads.

Single-Plot Stories

Older television shows (and even movies) usually had just one storyline that ran, for the most part, linearly. There was usually only one major plot (e.g. Spock, Kirk, and McCoy get stranded in the 1930s after stepping through the portal called The Guardian of Forever) and, occasionally, a few minor sub-plots (e.g. Kirk, surprisingly, finds the time to fall in love with Keeler). And we were usually shown these in chronological order unless, of course, there were flashbacks.

This is generally (not always!) what makes older stuff a little harder (i.e. a little boring) to watch. Though an episode like Star Trek: The Original Series' The City on the Edge of Forever is far from boring!

Multiple-Plot Stories

Then came the concept of the A/B storyline [3]. In this, two (or more) story threads (i.e. narrative plots) are developed simultaneously. The A-storyline is the main plot of the episode. For example, in Buffy the Vampire Slayer's Once More With Feeling, the A-storyline is the one in which the team investigates the spontaneous singing and bursting-into-flames phenomenon and tackles Sweet, the demon who has been summoned to Sunnydale and has caused all this mayhem.

The B-storyline, meanwhile, is a sub-plot that usually does things like character development, moving forward a developing story arc (i.e. a plot spread over a number of episodes), or supporting the main plot in some way or the other. In Once More With Feeling there are two main B-storylines. One is Tara finding out that Willow is abusing her Wiccan powers (and using them on Tara) and the second is Giles realizing that it is time for him to leave Buffy on her own (and for him to go back to England). The former doesn't figure much into this particular episode but the latter almost gets Buffy killed. You could say there are two more B-storylines going on: the first addressing the Buffy-Spike relationship and the second exploring the Anya-Xander relationship in more depth. Those are a little less important though, so you could even call them C-storylines!

Generally, though, shows produced after the turn of the century have lots of little subplots and storylines being developed in them all at the same time. That is, there aren't just two storylines, the A and the B, there are a few. Despite that fact, the phrase "A/B storyline" still generally works.

By the way, I chose Once More With Feeling to explain storylines specifically because each B-storyline literally gets its own song in that episode!

Craploads-of-Plots Stories

What's happening in television shows these days, though, is that there are many more storylines that just a handful. Lost is probably the first series to explicitly explore numerous storylines, character development arcs, and overall story arcs. This fact was initially daunting but, once you got used to it, all the storylines fit together and made sense. It was a little difficult, though, to start watching the series mid-season since you weren't quite sure what was going on. Also, Lost uses flashbacks to explain a lot of what is happening with its characters.

Heroes, which just started its second season in the US a few days ago, is the second major series to tackle this many storylines. In this they use both recaps and captions (that give you characters' names and locations) to help you figure out what's going on. That is particularly important for this series since, basically, it is narrated like a comic book.

The best thing about all this, then, is the fact that television shows are starting to become more compelling (narrative-wise, that is, since you have to have good writers on the show to be able to pull off that many simultaneous storylines and still make sense!); more in-depth with their stories (though, understandably they're a little slower with story development); and more prone to cult-like followings (since laypeople will find it hard to join mid-way...and once you're hooked, you're hooked). All of this, in my opinion at least, is a good thing.

Multiple, complex storylines = good.

Footnotes

[1] I have to stop using the words "cool", "awesome", "great", and "really".

[2] Or is it "A-B storyline"...I don't know.

[3] In television shows, that is. Plots and sub-plots have always existed in books.