A turn based strategy and role playing game by Squaresoft. It contains a complicated and well developed story about a war between rival kingdoms and the search for the Zodiac Stones which let demons manifest themselves through the stoneholders.
The combat plays out similary to a chess game, where in a battle, units take their turns moving and attacking on a grid. The max number of characters the player can use in a game is at most 5, although the player can have as many as 16 (I think) characters at his or her disposal. They gain experience and job points whenever they complete an action. The job points can be spent on abilities for the job (class) that the character is at the time. The characters can switch jobs between battles, and more and more jobs become available to the character as he/she gains levels in certain prerequisite jobs. Items can be bought for the characters between battles in shops at destinations (castles/cities) on the World Map (It's literally a map with dots as areas and lines between them.) Because of this setup. Almost all of the game is combat, with the rest being preparation and cutscenes in the story.
For a time the game was near impossible to find and it was selling for upwards of $100 at used game stores. After a few years it was finally made again as one of Playstation's Greatest Hits, and now should be much easier to find.
What, my definition isn't good enough? Buy Final Fantasy Tactics somewhere and check it out, it's only 10 bucks.