UPDATE: The Steelers compensatory pick in the 2015 NFL Draft has been changed. It was originally announced as a 7th round pick (252nd overall), but changed to a 6th round pick (212th overall) on March 25.
They are the draft picks that are added on to end of rounds three through seven in the NFL Draft, awarded to teams based on losses and gains during the previous year's free agency period.
For a team like the Steelers who like to build through the draft, they are treasured and welcomed, and sometimes can help land a key contributor.
This year the Steelers were awarded just one compensatory pick, originally announced as a seventh, but changed to a sixth round pick by the NFL, based on their 2014 free agency activity.
The Steelers signed five free agents last year who play into the equation, including: LaGarrette Blount, Darrius Heyward-Bey, Mike Mitchell, Arthur Moats, and Cam Thomas. Lance Moore was waived by the Saints and Brice McCain was waived by the Texans, and therefore they don't factor in.
The departures included: Ryan Clark, Jerricho Cotchery, Ziggy Hood, David Johnson, Emmanuel Sanders, and Al Woods. LaMarr Woodley didn't count as a loss because the Steelers waived him prior to the start of free agency.
Among the gems the Steeles were able to nab with a compensatory pick was Kelvin Beachum, the last of four picks the team had in the seventh round in the 2012 NFL Draft. Beachum went from a rookie who was a spot starter, to the team's starting left tackle in 2014.
The team also found linebacker Mike Vrabel, a third-round selection in 1997, running back Amos Zereoue in the third round in 1999, guard Willie Colon in the fourth round in 2006 and William Gay in the fifth round in 2007.
Last year the Steelers selected Dri Archer (third round) and Daniel McCullers (sixth round) with compensatory picks.
When this time of year rolls around next year, one thing to keep in mind. Had Jason Worilds not retired and signed with a team as an unrestricted free agent, the Steelers likely would have gotten one of the higher compensatory picks as a result. But because he retired, he doesn't count in the equation.