by Dr Philip Yip (Dell Community Rockstar and Microsoft Windows Insider MVP)
Windows 10 Insider Preview (Pre-Release Windows 10)
Windows 10 Test Cycle
Phase 1: Next Windows Release – The Latest Windows 10 Release. This Build has underwent minimal testing and not all Features "tried" may make it to the Final Release. This Build is Very Likely to be Buggy due to No Testing Before Release.
Phase 2: Fast Track – Features that are well received in the Next Windows Release get sent to the Fast Track for the Next Phase of Testing. This Build is Likely to be Buggy due to Limited Testing Before Release.
Phase 3: Slow Track – This is a Build of Windows 10 that will be very similar to the one released to the main user base. It is in the testing phase so this Build can be Buggy but has been tested in Phase 1 and Phase 2. Installation Media is Usually Available for this Track.
Phase 4: Main Track – This is the Build of Windows 10 released to the Main Windows Userbase. Installation Media is Always Available for this Track.
Phase 5: End of Life – This is a Previous Build of Windows 10 which no Longer has any Support or Security Updates. Users should Automatically be Updated to a Newer Mainstream Build of Windows 10 Before this Happens.