The Mythical Man-Month

There is so much good stuff in this book that it is hard to summarize it. The essence, at least as I understood it, is that the difficulties in the development of software comes from complex interrelationships. These relationships are partly bound by the complexity of the software written and partly by the necessary communication between the people working on it.

Some parts do show its age, but a lot is also timeless. Worth not just a read, but a re-read.

Worth noting: the 1995 edition has several extra chapters, which offers a good retrospective on the 1975 edition. The original is good, but the expanded edition is the one to get.