Is the sequel of Fate/Zero but is the oldest one it was produced in 2006. If you wach the anime and you like it then you should watch Fate/Zero too. If you Have not watch the anime yet then you should better skip it and watch Fate/Zero first and then go on Fate/Stay night...
Like i said Fate/stay night was first was produced but is better to see Fate/Zero first because is the first in STORY LINE.
About the story:
Fuyuki City is the setting for a secret and violent war among competing magicians. For the past two centuries, seven sorcerers have gathered and engage in a battle royale known as the Holy Grail War, each gambling his or her own life to obtain the Holy Grail, a legendary chalice capable of granting wishes.7 types of servants take part of the Grail those are:
1:Rider
2:Launcher
3:Caster
4:Assasin
5:Berserker
6:Archer
7:Saber
