TDD is a subset of automated testing as a whole. You'll find proponents of testing who might not actually like TDD. It's more of an opinion about the best appro

TDD is a subset of automated testing as a whole. You'll find proponents of testing who might not actually like TDD. It's more of an opinion about the best approach. Anyhow TDD is essentially writing the APIs, interfaces, and function signatures first, then writing tests, then implementing things under the hood, then getting tests to pass. Automated testing (unit or integration tests) is an extension of taking those little one-off things we do during development to make sure things work, and formalizing them to be a permanent part of the code base. Some people go further then and try to add tests for every feature or (gasp) every single line and sub-line of code. It's easy to get carried away with testing. And some people have valid arguments against testing. But it's nothing too hard or unapproachable. The point really is that everyone does testing already, but not everyone keeps all their tests and makes them nice.