In the US Army and the Joint community (which in doctrine follows the Army's approach), doctrine and doctrinal pubs form a hierarchy of how we go about our business. Doctrine informs action and is (there is debate on the degree) prescriptive. At the apex of the system are the Capstone documents: JP and FM 1.0 - N.0. Thus, JP 3.0 and FM 3.0 are both the overaching doctrinal manuals (textbooks) on Operations. 3-07 is MOOTW while FM 3-24 is COIN (operations), a subset within MOOTW (or SASO as the Army now calls it). Below doctrine are the Tactics, Techniques, and Procedures (TTP) pubs although there is some overlap. And, at the lowest level and most immediate are the Lessons Learned pubs from CALL and places like it. The latter pubs, based on experiences in the field in both combat and training exercises provide the raw input for doctinal modification along with other sources. Indeed, doctrinal pubs make a great effort to use empirical data in developing their texts.

That said, there is much that is wrong about the doctrine system. As has been said, it all too often becomes dogma and divorced from reality. Most of it is rewritten by iron majors and LTCs (slugs like us) under pressure of sometimes unrealistic deadlines, too much other work, not enough time to do real research, and a vetting process that may be more form than substance. It probably does produce better textbooks than are used in most civilian schools and universities but that is a pretty low standard!

As William Owen says, doctrine is what is taught. As Sam says, it is more than that - perhaps, a body of knowledge - but also less. Most important, it changes over time. And it is often ignored both to our sorrow and more happily when it really doesn't apply (as the WWII apochryful German complaint goes).