I am trying to read Mumford's *Geometric Invariant Theory*, however, I find my knowledge in algebraic geometry is inadequate. My knowledge is at the level of Hartshorne's *Algebraic Geometry*. Mumford cites a lot of results from EGA and SGA, but I cannot read French. Therefore, I want to ask:

What should I read if I want to read GIT?

I should mention that most of my knowledge is in differential geometry. I want to read Mumford's work to understand stable bundles and moment maps from another perspective; different from differential geometry.

Any suggestions for alternatives to Mumford's work will also be acceptable.

Stability of projective varietiesin l'Enseignement Mathématique, Vol.23 (1977), which is much more accessible than his book. It is freely accessible on the web. $\endgroup$