Microsoft are due to release Windows 10 in July 2015 and, perhaps as a response to the criticism and slow take up of Windows 8, Microsoft are offering it as a free update.

Well at least for the first year if you are running Windows 7, Windows 8 or Windows 8.1 (although not Enterprise editions). How much Microsoft will charge after the first year is at the moment unknown.

You can have a more indepth read over at PC Advisor or just Google Windows 10.