I was thinking about a possible *hierarchy* for the top three Grothendieck's works: EGA,SGA,FGA. But I haven't read all these works, and so I'm asking if there is actually such a hierarchy. 


Here the word hierarchy means a possible "reading path" of all these three works, which would be the first to be read in order to make basis for the second work and so on. 


Here the publication periods:


EGA - 1960-1967


SGA - 1960-1969


FGA - 1957-1962



Hierarchy of Grothendieck's SGA, EGA, FGA
In a few words: EGA is previous to everything, though one can use SGA 1 to complement some aspects of EGA IV. FGA goes "in between". There is a complicated tree for SGA. SGA 3 is independent of the rest while SGA 4, SGA 5 and SGA 7 are a full saga. SGA 6 is more or less independent but you need Verdier's thesis (or its resume at the end of SGA 4 1/2). In fact, SGA 4 1/2 can be considered as an introduction of certain aspects of SGA 4. FGA has three topics: formal schemes, duality and representable functors and should be read "as needed". The new edition of EGA I is a very nice reference.


It is perhaps interesting to point out that it is unrealistic try to master all of this material in a short amount of time. Perhaps one should study one of the manuals and then rely on EGA and SGA for further topics and additional details.


To mention a few good references (without being exhaustive): Hartshorne, Görtz-Wedhorn, Mumford-Oda, Liu and Bosch.


