For the past year, Microsoft has been annoyingly aggressive about getting people on board with Windows 10. If you've some how come this far without upgrading, the time has come to cast your die. The software is getting a big price hike starting July 30, from $0 to $179. SO UPDATE DAMMIT.
On August 2, Microsoft will be launching its anniversary update to the OS, which will also be free if you have Windows 10. Get in on all that free before it's too late.