Etching is an intaglio printmaking process. It goes back to the 15th/16th century. One of the most famous earlier practitioners was the Dutch artist, Rembrandt. The Rembrandt Museum, in the Netherlands, has a lovely little Flash animation that gives a visual overview of how an etching is made here.
This is basically the same process I use, except that my ground is acrylic, rather than asphalt and wax, because the acrylic does not require toxic solvents, and I use ferric chloride instead of acid (again, because it is safer).