February 16:
-Teams can designate their franchise/transition tag.
March 2:
-Before 4 p.m., teams must officially designate their franchise/transition tag.
March 2 (after 4 p.m.) - March 7 (before 4 p.m.):
-Clubs have exclusive rights to negotiate with their own players who are set to become unrestricted free agents.
March 7 (after 4 p.m.) - March 10 (before 4 p.m.):
-All teams can negotiate with all players who are set to become free agents.
March 10:
-Teams can exercise options for 2015 on players with option clauses in their 2014 contracts.
-Qualifying offers must be submitted to restricted free agents with expiring contracts.
-All teams must be under the 2015 salary cap prior to 4 p.m.
-All player contracts expire at 4 p.m. and the 2015 league year and free agency period begins.
To further explain what could occur from March 2-10, we will take a look at the Patriots current situation.
The team placed their franchise tag on kicker Stephen Gostkowski. Tagging Gostkowski means that Devin McCourty is set to become a free agent. However, the Patriots will have exclusive rights to talk with McCourty from March 2 to March 7. If no deal is reached between the two sides by 4 p.m. on the 7th, then the other 31 teams in the league can talk with McCourty about potential deals until March 10.
After 4 p.m. on the 10th, those deals can be signed and become official.
It's also important to note that those who have been tagged can also work out long-term deals with their respective teams through July 15.