Ubuntu component summary

Ubuntu has four components, they are grouped according to License Policy.

• Main component contains free software and fully supported by Ubuntu.
• Universe component contains free softwares from open source world. They are not guaranteed with fixed by Ubuntu.
  
• Restricted component contains popular software which is not completely free. Ubuntu team supports the software. (The support may not complete because the license may prohibit Ubuntu from modifying for the bug fix.)
• Multiverse component contains non-free software

Here is a summay table.

	Free software	non-free software
Offical Support	main	restricted
Unofficial	universe	multiverse

Reference documents:
http://wiki.ubuntu.com/Ubuntu/ForDebianDevelopers
http://http://www.ubuntu.com/community/ubuntustory/components