This summary assumes you already know the basics of the item system given by the game itself.
Most of this information can easily be found on the official TF2 wiki:
This topic is intended as only a quick guide for those in a hurry.
What can I do to influence drops?
Drops are based on playtime alone. There is no in-game metric that influences drops.
According to the TF2 team, this was done for two basic reasons. First, tracking in-game performance is near-impossible because servers can easily use plugins or modifications that lie about these things. Second, the TF2 team did not want to have any influence on how people played the game, and they believe that any in-game performance tracking would have an inherent bias toward specific classes, maps, or tactics.
How often will I get drops?
What varies is time between drops. Players are guaranteed to find items at intervals between 30 to 70 minutes, with an average interval of about 50 minutes.
What is the drop cap?
The drop cap is based on time played. There is no cap on the amount of items that can be received per week. The cap has been estimated to be around 10 to 11 hours a week. Playtime beyond the cap will not lead to more drops. Playing less than the cap carries over any leftover time to a maximum of double the normal cap (20 to 22 hours).
Have I reached my drop cap?
The cap is around 10 to 11 hours a week. To be absolutely certain that you have hit your cap, try to determine about how much time has passed since your last drop. Remember, the maximum time interval between drops is 70 minutes.
How many drops will I find a week?
Most players report finding between 7 to 12 drops a week.
However, assuming a cap of 10 hours, the number of drops has a theoretical minimum of about 4 and a theoretical maximum of about 20, not including additional drops caused by Achievement milestones or Duel Mini-game victories.
When does the cap reset?
The cap resets at approximately Thursday 0:00 AM GMT, or around Wednesday 19:00 (7:00 PM) EST or Wednesday 16:00 (4:00 PM) PST
Why can't I find my drop in my backpack?
Drops (and any item obtained via trading, crafting, etc.) may seem to disappear temporarily. This can usually be solved by dying in a server, disconnecting from a server, or visiting the Mann Co store.
What are the other ways to get items?
Gaining an achievement milestone automatically drops a specific item tied to that milestone. Winning 10 Dueling Mini-games automatically gives another 5-use Dueling Mini-game and a random drop item. Obtaining items this way does not affect the drop schedule or drop cap.
Do items drop at different rates?
Yes. Weapons or items that make up an "item set" are known to drop at different rates relative to one another. Items that are not in an "item set" are believed to drop at the same rate.
What about crates, hats, tools, etc.?
Crates have been confirmed to drop on a different schedule, so finding a crate does not mean you were cheated out of a different drop. Tools (paints, name tags, dueling mini-games) and cosmetic items (hats) are believed to drop on a separate schedule as well, but it has not been confirmed.
In case there's another double-drop week, how do double-drops work?
During "double drop weeks," the interval between drops is halved, becoming 15 to 35 minutes instead of 30 to 70 minutes. The drop cap remains unchanged. You should find about twice as many items as usual.
What items drop more frequently or rarely in an item set?
The relative drop rates have never been released or confirmed. However, based on community reports, the following sets likely have this distribution:
Common: Holy Mackerel
Rare: Shortstop, Mad Milk
Common: Battalion's Back-up
Rare: Black Box
Common: Ullapool Caber
Common: Brass Beast
Rare: Buffalo Steak Sandvich, Warrior's Spirit
Rare: Crusader's Crossbow
Common: Darwin's Danger Shield
Rare: Sydney Sleeper, Bushwacka
Rare: Your Eternal Reward
Remember, the above distribution is speculation by the community and may be incorrect. There is no guarantee that the relative drop rates will not change either.
Item sets for the Uber Update have been released too recently to have definite estimates on relative drop distribution.
NO! 3 STICKIES IS ENOUGH!
"Have you got a Paradox sig yet?" "No, but I'm watching him closely." - Arleas
No, I think this is a very good thing to sticky since the drop system is a mystery to new and old players alike
Bump. This is a very useful post. Especially for the F2P players.
Thanks TC, I really had no idea how the drop system worked before I read your post.
I'm 99% sure everything in the non official info post is false
Best weapon combo in tf2: http://www.youtube.com/watch?v=7oUWPbS4450&feature=channel_video_title
From: iammaxhailme | #008
That's OK, some of the "official" stuff isn't entirely correct either.
NO! 3 STICKIES IS ENOUGH!
Hat Count in TF2: 3. http://www.tf2items.com/profiles/76561198032105695
Add user to Ignore List after reporting