It also found it helpful to learn some (algebraic) number theory, to get a sense of where some of the motivation comes from (e.g. elliptic curves, modular forms). Grothendieck's work is abstract, but he was always motivated by concrete problems (e.g. Weil conjectures).
Some resources I have used are:
* video lectures by Richard Borcherds
* Lecture notes by Andreas Gathmann (https://www.mathematik.uni-kl.de/~gathmann/class/alggeom-200...)
* This blog: https://rigtriv.wordpress.com/ag-from-the-beginning/
* An infinite large napkin, by Evan Chen (https://venhance.github.io/napkin/Napkin.pdf)
It also found it helpful to learn some (algebraic) number theory, to get a sense of where some of the motivation comes from (e.g. elliptic curves, modular forms). Grothendieck's work is abstract, but he was always motivated by concrete problems (e.g. Weil conjectures).