The NFL's free agency period begins on Tuesday at 4 p.m. Here is everything you need to know about one of the most interesting days of the NFL calendar.

What is the salary cap?

The 2012 salary cap is $120,600,000

How much money does each team have?

That is a tough question to answer about any team as there are about 60 pages of rules and regulations regarding the salary cap in the current CBA, basically, its complicated. However, Adam Oestmann at lists this for each team as of Sunday night.

  • Bengals:  $49.9 million under.
  • Broncos:  $44.7 million under.
  • Buccaneers:  $42.7 million under.
  • Jaguars:  $40.6 million under.
  • Chiefs:  $32.5 million under.
  • Redskins:  $31.1 million under.
  • Bills:  $30.8 million under.
  • Seahawks:  $29.8 million under.
  • Titans:  $28.1 million under.
  • Bears:  $22.6 million under.
  • 49ers:  $21.8 million under.
  • Browns:  $17.4 million under.
  • Patriots:  $16.2 million under.
  • Chargers:  $14.9 million under.
  • Ravens:  $14.45 million under.
  • Dolphins:  $11.8 million under.
  • Colts:  $11.6 million under.
  • Steelers:  $10.5 million under.
  • Eagles:  $9.6 million under.
  • Vikings:  $7.9 million under.
  • Jets:  $7.1 million under.
  • Falcons:  $5.8 million under.
  • Packers:  $5.4 million under.
  • Saints:  $5.2 million under.
  • Cowboys:  $4.7 million under.
  • Rams:  $1.2 million under.
  • Giants:  $3.8 million over.
  • Texans:  $4.7 million over.
  • Panthers:  $5.3 million over.
  • Raiders:  $7.4 million over.
  • Lions:  $11.5 million over.
  • Cardinals:  $16.4 million over.

Who is available?

The top prize in the 2012 free agent list is obviously Peyton Manning, but there are lots of other impact players who will be appearing in new uniforms next season.

On offense, veteran wide receivers Marques Colston and Vincent Jackson are available. Both are big bodies that can be legitimate number one receivers for whoever grabs them.

Up front, Carl Nicks is a huge prize. He is 26, and at the top of his game right now. After him, players like Evan Mathis, Chris Myers and Ben Grubbs are at the top of the class although Mathis and Myers are 30 and Grubbs is coming of an injury that cost him six games of the 2011 season.

At running back, New England's Benjarvis Green-Ellis and San Diego's Mike Tolbert lead the class. Both are capable every down backs though both are probably better suited to be part of a rotation. Tolbert's tendency to fumble hurts him.

Under center the class is very thin after Manning. Aaron Rodgers back-up Mike Flynn is available and could be brought in by some team to provide competition for the starting job in camp. The 26 year-old has been impressive in very limited action in Green Bay and maybe he is poised for a breakout, but he is not a sure thing.

On defense, Texans defensive end Mario Williams is available. He has 53 sacks over six seasons and is one of the premier pass rushers in the league. He missed most of last season with a torn pectoral muscle, but it shouldn't hamper him this season.

Jeremy Mincey, Paul Soliai, and Brodrick Bunkley are also available on the defensive front. All three are young, experienced and capable of being solid every day players in the trenches.

Linebacker is one of the deepest positions in the draft. Players like Stephen Tulloch, David Hawthorne, Erin Henderson and Manny Lawson lead the class, but they are just scratching the surface for any team in need.

Defensive back is similarly stacked. Courtland Finnegan and Brandon Carr are the big names at corner, but William Middleton is also an attractive option. LaRon Landry is also an attractive piece as a deep safety but injuries have hurt him.