This year, the mouse replaced the remote

If you want to see what happened on TV this year, holster your remote and grab your mouse.

Then start pointing and clicking. Television by the gigabyte awaits you on the Web.

In 2006, that accounted for much of the big news about TV, as its programming migrated online – television’s new frontier.

The trend had begun in late 2005 with ABC selling episodes of some of its shows through iTunes. By this fall, the broadcast networks were making hundreds of hours available for free download.

But that wasn’t all. Scrambling to stake their claims in a new medium, the networks supplemented hand-me-downs with original content: previews, highlights and other “Web exclusives.”

Sci Fi created “webisodes” of “Battlestar Galactica” as a get-acquainted aid before the series’ new season began on the network in October. ABC introduced a mid-afternoon “World News” edition tailored for the Web. NBC Webcasts took “Saturday Night Live” fans backstage at the show.

But, even with all the new content, viewers weren’t content to just sit and watch. This year marked the coming-of-age for participant TV – or, to put it another way, the YouTube Age.

Officially launched a year ago, that video-sharing service instantly established itself as an archive of explosive proportions, boasting everything from stupid pet tricks and amateur porn to clips of breathtaking artistry – along with much of the best material airing on television, legally obtained or otherwise.

In this new, wide-open game, the TV industry scrambled to keep up.

One strategy to hook viewers: more dramatic serials. Taking a cue from addictive hits like “Lost” and “Desperate Housewives,” the networks this fall unveiled one open-ended drama after another – too many, in fact, for busy viewers to keep up with.

NBC’s “Heroes” proved heroic, but Fox’s “Vanished” did just that, and “Runaway” quickly ran aground on the CW, a new hybrid network formed from the merger of UPN and the WB.

While anxiously watching its bottom line in 2006, each network was also pointedly reminded to watch its language. In June, Congress passed a bill to boost tenfold the fines imposed by the Federal Communications Commission for airing indecent content – from a maximum $32,500 to $325,000 per incident.

A planned November interview with O.J. Simpson on Fox – in which the former football star divulged how hypothetically he could have killed his ex-wife and her friend – might very well have ranked as the year’s most indecent program.

That is, if it had aired. But shortly after its announcement, “O.J. Simpson: If I Did It, Here’s How It Happened” was yanked (along with an accompanying book) in response to public outcry.

In 2006 – as in the year before, when death claimed anchorman Peter Jennings – tragedy stalked ABC News. In January, Bob Woodruff, just a month into his tenure as Jennings’ successor (with co-anchor Elizabeth Vargas), was seriously injured in Iraq while covering the war. Ongoing therapy kept him sidelined all year.

In May, ABC announced that Charles Gibson instead would anchor “World News” and, in June, he toasted the end of his nearly 19 years hosting “Good Morning America.” On that final broadcast, he was surrounded by his family, with Kermit the Frog perched on his shoulder.

There was plenty more leapfrogging on the network scene.

On April 5, Katie Couric divulged her plans to leave NBC’s “Today” show to anchor “The CBS Evening News.” The next day, Meredith Vieira – who anchored ABC’s daytime talk show, “The View” – was named as Couric’s successor. Three weeks later, Rosie O’Donnell got the nod as Vieira’s replacement.

On Sept. 5, O’Donnell got a rousing welcome to “The View.” That evening, Couric began her reign as the first woman hired as solo anchor for any of the three network nightly newscasts.

A week later, Vieira made a smooth start beside Matt Lauer at the “Today” anchor desk, declaring she felt “like it’s the first day of school and I’m sitting next to the cutest guy.”

Not that her old show didn’t make a little noise in her absence.

In November, a hard-partying Danny DeVito arrived at “The View” to plug his new film. Explaining he’d spent a late night out with George Clooney, DeVito slurred his speech and used some racy language on the live broadcast.

But that was nothing compared to Michael Richards. On Nov. 20, he made a memorable appearance on the “Late Show with David Letterman” where, looking stricken, he delivered an apology for his racist rant in a West Hollywood comedy club three days before.

Richards’ tirade against several black members of his audience (ignited, said the former “Seinfeld” star, by audience heckling) was captured on a cell phone. Then the video was posted on the TMZ.com Web site. Then on YouTube and elsewhere. Seen on PCs around the world. And quickly picked up by TV for further exposure.

Richards, who initially won stardom on TV’s traditional terms, now was socked with something new: a brand of celebrity beyond no one’s reach, born in the digital age.

It was that kind of TV year.