Produced by ABC News, the five-part series “Hooking Up” (8 p.m., ABC) welcomes viewers to the frantic world of Internet dating. According to “Hooking Up,” the Internet has revolutionized the dating scene. Long gone are the furtive “Miss Lonely Hearts” want ads and professional dating establishments. But as one participant observes, “Internet dating is not for losers, but you can find plenty of losers dating on the Internet.”

During the course of the first hour, we follow a 30-something female gynecologist who seems eager to find love online, but reluctant to reveal her profession or image for fear that colleagues and patients may find out. Her date with a fellow physician proves both furtive and frustrating. An attractive and brazenly self-confident hair salon manager finds that the photos posted online can be a decade or so out of date.

Tonight’s other highlights

¢ Julie Chen is host on “Big Brother 6” (7 p.m., CBS).

¢ A concert missed on “The O.C.” (8 p.m., Fox).

¢ On back-to-back episodes of “Will & Grace” (8:30 p.m., NBC), an hour-long Thanksgiving special (8:30 p.m.), a broken keepsake (9:30 p.m.).

¢ A killer lives large at a plus-size convention on “CSI” (8 p.m., CBS).

¢ An elderly juror vanishes on “Without a Trace” (8 p.m., CBS).

¢ Scheduled on “Primetime” (9 p.m., ABC): the popular appeal of a South American spiritual leader named “Father John.”