👉 A pullback or pullback fibration is a special type of fibrant replacement construction that arises in algebraic geometry. It generalizes the notion of a pullback along a morphism, and it allows one to obtain a new structure on an object by "pulling back" its values under a given morphism. In the context of algebraic geometry, a pullback is used to construct a pullback fibration between two schemes (or more generally, schemes over a topological space).
