Free Agency officially begins at the end of this month.  Ask the Commish writes an excellent summary of the NFL's free agency rules, which, I warn you, are very complex.  The key difference between a UFA and a RFA is pretty straightforward - a UFA has the right to sign with any team he chooses without his team demanding compensation.  The RFA differs in that the player's team can benefit from having the right of first refusal which alows it to match the player's best offer.  In some cases, as outlined by Kirkendall using the example of DeDe Dorsey, the team can demand draft compensation.  UFAs must have been in the league for 4 or more seasons.  RFAs must have 3 or more "accrued" seasons but less than 5.

Each club can designate one of its players who would otherwise be a UFA or RFA as the"Franchise Player."  According to the Commish, most people don't realize the Bengals have the option of designating the Franchise Player with one of two tags: "Exclusive" or "Non-Exclusive."  Any club that designates a Franchise player as "Exclusive" shall be the only club that the player can sign with at a salary that is the minimum of the average of the top five salaries in the league at his position or 120% of his salary, whichever is greater.  If the team elects to name the player "non-exclusive" then the player shall be permitted to negotiate a contract with any club as if he were an UFA, however draft compensation of TWO first round picks will be awarded.  If the player elects to play with the team that designated him with the Franchise tag, the one-year salary is guaranteed.  Teams must designate the Franchise player between Feb 5-19th. 

Teams must submit a qualifying offers to their RFAs by Feb. 26.  Free Agency then officially begins on Feb. 27.

I hope this helps.  Ask the Commish also reports that the Bengals have the 12th- most cap space available to sign rookies and free agents so they will have options in terms of wading into the free agent market.  Again, I would like to see them sign a veteran leader who can bring a bit of "nastiness" to our O-line.