This was/is a Friday night block of comedies. The name comes from the expression "TGIF," an abbreviation of "Thank God It's Friday," though apparently ABC's usage of the name meant "Thank Goodness It's Funny." (I'm not sure if that's what it really meant throughout its run, or just in the beginning. Considering it was a Friday night lineup, it makes sense to assume the "F" in the block's name really stands for "Friday.") Anyway, I guess it technically began in 1989, but I didn't really have access to ABC until 1995. I was probably at least vaguely aware of the block before that, but even so, I tend to associate TGIF with the 90s (just like NBC's Must See TV). And, as with the NBC block, Wikipedia's article has a grid that lists shows that aired during the block's run (which initially ended with the 1999-2000 season, but was revived for two more seasons starting in 2003, and later for a third run starting in 2018), and also like the other block, the grid lists some seasons that fell outside the run of the block (though not nearly as many as with Must See TV). Unlike Must See TV, I'm not going to try to list every show that aired during the block's run, just the ones with which I'm at least slightly familiar. Some of the shows in this block, I had seen on a Canadian channel before I ever got ABC.
First run
1989-90
The initial lineup included Full House (1987-95), Family Matters (1989-97; moved to CBS for 97-98 season), Perfect Strangers (1986-93), and "Just the Ten of Us" (1988-90), the latter of which I've never seen.
1990-91
Mostly the lineup remained the same, though there would be some shows I've never seen. Also, in spring 1991, Dinosaurs (1991-94) joined the lineup.
1991-92
Again there would be some shows I've never seen, though one that I've seen a bit of was Step by Step (1991-97; moved to CBS for 97-98 season).
1992-93
As usual, some shows continued, and some new shows I've never seen debuted.
1993-94
Boy Meets World (1993-2000) joined the lineup. So did "Hangin' with Mr. Cooper" (1992-97) and "Sister, Sister" (1994-95; moved to the WB for 95-99), both of which I probably saw a bit of.
1994-95
Lineup remained mostly the same, except for one new show I never saw.
1995-96
Lineup remained mostly the same, but a couple of shows debuted in spring 1996: Muppets Tonight (1996-98) and Aliens in the Family (1996).
1996-97
Sabrina the Teenage Witch (1996-2000; moved to the WB for 2000-03) debuted, as did Clueless (1996-97; moved to UPN for 97-99).
1997-98
"You Wish" (1997-98) debuted, along with Teen Angel (1997-98). One night this season there was a crossover event between those shows, as well as Sabrina and Boy Meets World.
1998-99
Sabrina and Boy Meets World continued; there were a couple of new shows I never saw.
1999-2000
Again, Sabrina and Boy Meets World continued, and there were some new shows I never saw.
2003-04
I saw a little bit of "Hope & Faith" (2003-06), just because my sister watched it. And I saw some of Life with Bonnie (2002-04). And I think I probably saw a bit of "George Lopez" (2002-07), but I don't really remember. There were a couple of shows in this season's lineup that I definitely never saw.
2004-05
I saw a bit of "8 Simple Rules" (2002-05), just because my sister watched it. And I saw a bit of "Less Than Perfect" (2002-06). Also this season, Hope & Faith continued, and there was a new show I never saw.
2018-19
The relaunch of the block includes the fifth season of Fresh off the Boat (moving from Tuesdays to Fridays) and the third season of Speechless (moved from Wednesdays to Fridays), as well as the second season of the game show "Child Support."
2019-20
The fourth season of American Housewife (moved from Wednesdays to Fridays), followed by the sixth season of "Fresh off the Boat."