Compilers by aho and ullman pdf

What is compiler generated tool?
In computer science, a compiler-compiler or compiler generator is a programming tool that creates a parser, interpreter, or compiler from some form of formal description of a programming language and machine.
The most common type of compiler-compiler is more precisely called a parser generator..
The phases of a compiler represent the sequential stages through which source code is transformed into executable code.
These phases include lexical analysis, parsing, semantic analysis, optimization, code generation, and code optimization.

What is compiler generated tool?