There is little to add to what Caring Together says about Myers-Briggs Personality types that isn’t easily accessible on the net.
Starting on the basics page of the Myers-Briggs Foundation’s own site will give you the fundamental information and then exploring other pages on it will give you the official version.
Personality Pathways also has an excellent summary.
The Myers-Briggs approach is very widely used but has been criticised for being rather vague and general and certainly shouldn’t be used to test people’s suitability for a particular job or task. It is primarily ‘a framework for understanding individual differences, and … a dynamic model of individual development’.
There are of course other techniques for testing and discovering personality types.