Native feature under MacOS X, virtual desktops (Spaces) allow you to reorganise your windows by creating additional desktops, allowing you to separate and store the different open applications. This tutorial will allow you to increase this number.
Open System preferences using Spotlight then click on Presentation and Spaces. On the tab Spaces, start by activating Spaces (if not already done) by ticking the appropriate box.
Then, set a number of rows and columns using signs +.
By default, you have 4 virtual desktops but this number can be extended to 16 which is very appreciable for those who are accustomed to opening a whole bunch of applications simultaneously.