Proof of the Erdős-Szemerédi sunflower conjecture

In the 1970s, Erdős and Szemerédi conjectured that for any $n\ge k-1\ge 2$, any collection of subsets of $[n]$ not containing a $k$-sunflower has size at most $c_k^n$ for some $c_k<2$. In the $k=3$ case, this follows from the work of Croot, Lev, and Pach and Ellenberg and Gijswijt on the cap-set problem, through a reduction due to Alon, Shpilka, and Umans. We prove the conjecture for every $k\ge 3$.