Over the next few days we’ll be taking a look at some of the best NFL players ever, in an attempt to give you a passing familiarity with some big names that are likely to be thrown around at the water cooler or Super Bowl party.

Today’s position: Defensive Back. NFL Defensive Backs (commonly referred to collectively as the “defensive backfield” or “secondary”) include three distinct positions: Cornerback (CB) and two different Safeties—the Strong Safety (SS), and Free Safety (FS). In general, modern NFL teams play most of their “vanilla” defensive formations with two cornerbacks and one of each safety, for a total of four defensive backs. Since these positions aren’t quite as obvious as others, we’ll spend a little time going over what they do. Their duties vary depending on the particular defensive formation and play called, but for the most part:

Cornerbacks are the guys lined up directly across from and facing the offense’s wide receivers, usually around four yards off the line of scrimmage. They will often try to disrupt the receivers by pushing them off their routes at the beginning of a play. Afterwards they will typically either try to stay on their assigned receiver (man coverage) or drop back and defend a particular area of the field (zone coverage). Of course, depending on the specific play, they could be asked to stay put and defend a short zone in the flat, attack the ball carrier to stuff the run, or blitz the quarterback.

Sometimes you will hear announcers mention that a defense is playing in a “nickel” or “dime” formation, or they may refer to “nickelbacks” and “dimebacks”. Fortunately this has nothing to do with obnoxiously untalented Canadian rock bands; instead, it means that the defense is playing with either three or four cornerbacks instead of just two. In the case of the nickel formation, the defense adds one cornerback called a nickelback to the lineup; for the dime, they add both a nickelback and a fourth corner called a dimeback. Obviously, this is most often done in situations where the offense is likely to pass.

Safeties line up 10 to 15 yards deep in the defensive backfield, furthest away from the offense. Most plays will have the free safety in a deep zone while the strong safety might cover a deep zone, a more shallow zone, or even play man coverage on a receiver or tight end. Of course, either safety may be asked to blitz.

As with cornerbacks, the coach may decide he needs more than two safeties. Often this will be in a “quarter” formation, which includes both the nickelback and dimeback, as well as an additional strong safety.

Still awake? There have been many exceptional defensive backs over the years, and there are several greats currently in the NFL, with Denver’s Champ Bailey and Baltimore’s Ed Reed at or near the top of the heap this past season. You’ll see a couple great corners in the big game Sunday, when Chicago’s Charles “Peanut” Tillman and Devin Hester (who, while technically a defensive back, is used as a dominating, record-breaking kick returner) take the field.

Perhaps the one guy all these DBs want to be, whether they know it or not, is Mel Blount. Mel played for the Steelers for 14 seasons, recording four Super Bowl victories (IX, X, XIII, and XIV) with key interceptions in IX and XIII. He went to the Pro Bowl five times, and pretty much set the bar for defensive back greatness with 57 career interceptions. Mel was inducted into the Pro Football Hall of Fame in 1989.

A few years later the Steelers were graced with another spectacular defensive back in Ron Woodson, who ended up being successful at both cornerback and safety during his career. Woodson holds current NFL records for number of interceptions returned for touchdowns (12), as well as interception return yards (1,483).

Any article about defensive backs would be incomplete without mentioning “Neon” Deion Sanders. Despite releasing a depressingly awful rap album and appearing in an MC Hammer video, the guy was a gifted athlete and had several fantastic seasons with the Atlanta Falcons, where he snagged 24 interceptions in five seasons before skipping town for San Francisco and a Super Bowl ring in 1994. He then went on to the Cowboys and another Super Bowl victory in Super Bowl XXX, where he both intercepted a pass on defense and caught a 47-yard pass to set up a touchdown on offense. He retired in 2001, but came back in 2004 (at age 37) to play for Baltimore, where he moved himself into second place behind Ron Woodson for the NFL interceptions returned for touchdown record, with 9.