Recently, Balogh--Morris--Samotij and Saxton--Thomason proved that
hypergraphs satisfying some natural conditions have only few independent sets.
Their main results already have several applications. However, the methods of
proving these theorems are even more far reaching. The general idea is to
describe some family of events, whose cardinality a priori could be large, only
with a few certificates. Here, we show some applications of the methods,
including counting C4-free graphs, considering the size of a maximum
C4-free subgraph of a random graph and counting metric spaces with a given
number of points. Additionally, we discuss some connections with the
Szemer\'edi Regularity Lemma.Comment: This is a survey style paper written for the IMA volume "Recent
Trends in Combinatorics" for the 2014-2015 Annual Thematic Program Discrete
Structures: Analysis and Applications at the Institute for Mathematics and
its Applications during Fall 201