Manifests are puppet configuration files. they are used to describe functions, nodes, and installation classes.
It is good practice to separate out different functions, putting nodes in nodes.pp and functions in functions.pp or a similar naming convention. We default to making a new manifest for each class we define.
The first manifest is the master manifest (site.pp), it lists the other manifests that puppetmaster will load. puppetmaster only knows to load site.pp