Last night, I spent a little time talking to the mother of a young man who’s still hoping to secure a place in an NFL camp. She needed help breaking down exactly what the landscape looks like for a player who’s on the outside looking into the football world.

Today and tomorrow, rookie mini-camps start for 24 of 32 NFL teams (here are the teams that go to camp next weekend). Most of the players in these camps are rookies (with a  few street free agents sprinkled in here and there) in one of three categories: draftees, undrafted free agent signees (UDFAs) and tryout players. Most teams will bring in around 25-30 players between all three categories for their rookie mini-camps.

It’s important to understand the difference between these players. Draftees, in most cases, will not have signed contracts. Their agents will take care of that at some point in the coming weeks. Undrafted free agents, in all cases, do have contracts. Most sign a standard, no-frills, three-year deal with various signing bonuses (usually ranging between $15,000 and $500). In all cases, tryout players do not have contracts. They are competing for the right to sign an undrafted free agent contract. For that reason, tryout players do not count against a team’s 90-man roster. It’s not uncommon for teams to bring in 20 or more tryout players. What do they have to lose?

I should mention here that tryout players are essentially trying to win a lottery for which the prize is another lottery ticket. A lot of people don’t understand that tryout players are seen as the ultimate fringe players by scouts, utter longshots. These days, I see a lot of agents posting on Facebook how their clients are in the league. Well, no, they really aren’t.

In fact, the NFLPA requires all contract advisors to get at least one player on a 90-man roster (i.e., the offseason, when rosters are fat) in a three-year period, but tryout players do not count toward that total. So even if an agent works extremely hard to get a player on a roster – and many do – if he doesn’t earn a contract in his three days with the team, it’s as if the player never existed for the purposes of the NFLPA. So that’s an important differentiator.

Because some teams choose to have their rookie mini-camps the second weekend after the draft, tryout invitations are rather fluid, and it’s not uncommon to see players accept two tryout invitations. Why not? If he makes the team on the first tryout, he can let his agent deal with the other team. There’s certainly nothing barring a player from taking part in two tryouts.

While most UDFA deals are signed in the first hour or so after the draft, teams may take a week or more before they’re doing handing out tryout invitations. There’s also no set policy on how players get to the team for tryouts. I’ve heard that some teams will bring in a player for a tryout, but just as often, a team will bring in local players for tryouts so they can contain costs.

As you scan your favorite team’s site for more post-draft crumbs, hopefully this helps clear a few things up for you, especially if you have a son who’s still nursing NFL ambitions.