What you have before you is the book I would have liked to have studied a few years back when when making an effort to learn the subject of K-theory. It is my impression that - despite the massive promotion of K-theory in recent years - there is still a severe lack of introductory, yet thorough,
expositions of this theory that everyone seems eager to learn. Actually, the present notes were, in the beginning, written to teach myself the 'missing
links' of K-theory, i.e. the detailed arguments and techniques that I could not find in print anywhere.