The document discusses intermediate code generation in compilers. It explains that intermediate code serves as a bridge between the high-level source code and final machine code. It presents different types of intermediate representations like syntax trees and three-address code. Syntax trees abstract away details from parse trees while three-address code translates expressions into a linear representation using temporary variables. The document also provides examples and explanations of different data structures used to represent three-address code like quadruples and triples.