Fate/stay night was originally a game developed by TYPE-MOON, and is also the first creation which TYPE-MOON made after going into business (instead of being a group of Doujinshi people).

Seven Masters, Seven Servants. Only one can correspond to the Holy Grail

In the legend, the Holy Grail is an artifact that can make your wishes come true, in order to summon the Holy Grail, a ceremonial is required. The seven Masters chosen by the Holy Grail will be granted the seven Servants chosen by the Holy Grail: Saber, Lancer, Archer, Rider, Caster, Assassin, and Berserker. The Master must prove him/herself that he or she is the only one qualified to use the Holy Grail. In other words, he or she must defeat all the other Masters to prove him/herself.

Shiro Emiya lost his parents in a fire when he was young, and was adopted by a magician, even though he denied teaching Shiro magic, the un-talented Shiro still master a little. When the magician died, Shiro remained a worthless magician. Entangled with the "War of the Holy Grail" by accident, Shiro was granted the Servant "Saber" and was chosen to be one of the seven Masters.

Credits: kulthuzard

Humor:
There...is humor content involved.But in the later part of the plot,the humor content is usually interfered by serious "stuff" the next second which kinda hampers the mood :P

Overall:
This Anime is quite enjoyable to be honest.The combat scenes might be some what short but their well drawn one way or the other. (I always get stuck at writing the Presentation since I written everything else in Story,Sound & Art T_T ) Either way,it's going to be troublesome to follow the entire plot of the series since...well read the Trivia section...

Trivia:
-Fate/Stay Night (Anime) was adapted from the Adult Visual Novel version which is being cut into several phases.The Anime version is a highly compressed version of the visual novel.HOWEVER.