How to create multiple libraries in iTunes and iPhoto

Surely many times I had asked as photos or music stored in iPhoto or iTunes on external hard drives.
By default iTunes or iPhoto libraries stored on the primary hard drive, which means that increasingly we have less disk space. Believe it or not there is a way to create new libraries in these programs so that music or photos are stored on external hard drives:
Both iTunes and iPhoto can create as many libraries as you want. When you open any of these programs, hold down the alt key and opens a dialog that lets you create or select the library you want to use at that time.

A main library on an external hard drive, with all the songs and pictures of life, and a small library with the favorites in the inner disk of the Mac is your thing, very comfortable and saves a lot of disk space.