Good to know. So I'm actually practicing CI the way that I work, I'm just not paying some company monthly fees for a CI server. So the difference between CI the practice and "CI wink wink" is $$$.
What there is to a complete CI process depends on what your release process is, apart from the build process. There may be code signings, integration with external services etc. These are steps that are not part of the individual developers build process.
The letter I in CI stands for integration. Two checkins might very well look good on their own, but cause havoc with other systems.