XP is a not quite accurate acronym for Extreme Programming. This was developed by Kent Beck when he worked for the Chrysler Corporation in the 1990s, and is another widely-used and well-known "flavour" of Agile.
Like most things to do with Agile, XP was first developed as a methodology for software development, but has been adapted and utilised for all forms of project management since its origin.
In common with all Agile practices, XP has a responsive element and delivers stages of the project incrementally, allowing for requirements updates and improved productivity. Other elements of XP include Pairing - where 2 people work on the same issue at once - and focusing on features of the project only when they are required.
I get asked the question ‘who is your favourite 19th century Prussian Field Marshal’ quite a lot, as I suspect you do as well. There are of course several great contenders for this title, but my vote has to go Helmuth Von Moltke the Elder. Why? Because of his contribution to the concept of dynamic planning! Trying to convince people that planning is a continuous and never ending process and not something that’s completed at the start of a project is a constant challenge for me and I will grab any support I can get.