Staking

Action to send your $PAW to an external account

That $PAW is locked (you can't use it) for a undetermined period (you can un-stake when you want)

You can unstake at any moment BUT you'll have a "unstaking period" before the $PAW gets back to the sending account (depending on the pool)

Staked $PAW do generate rewards, depending on the pool it is staked on. At the moment there are 180 and 90 days pools

When $PAW is in "unstaking state" they stop generating reward. So during that period :

• $PAW is not on your account (it is still on the staking account for the unstaking period of time, you can't use it)
• $PAW amount doesn't generate staking reward (so no auto-stake, as auto-stake is putting back rewards on staking account)
• $PAW still accounts for Tribe Delegation (see below)

Delegating

Action to provide voting weight to a tribe

That $PAW isn't locked, it remain on your account, you can use it as you want

Your account is linked to a representative tribe. That tribe  gets more voting weight, so more network reward and may (or not) reward you for that

NOTE : if you have a staking account linked to that base account, delegating the base account to a tribe will also delegate the corresponding staking account

Tribe

Also known as a node on other chains. 

From the official FAQ:

PAW secures the network with animal tribes who vote on the validity of a transaction
The process works like a democracy, where your delegated PAW to a tribe is voting on your behalf.
In the PAW network the balances from all delegated PAW are resposible on how much weight a tribe in the voting for a transaction has.

Joining a tribe means delegating your PAW to that Tribe, thus giving more weight for the Tribe to vote (more info on joining/delegating to a tribe in https://www.publish0x.com/paw-faq/how-do-i-delegate-my-dollar-paw-to-a-tribe-xznkkjw )

List of tribes can be found at : https://tribes.paw.digital 

DAG - Directed Acyclic Graph

A directed acyclic graph or DAG is a data modeling or structuring tool typically used in cryptocurrencies. 

Unlike a blockchain, which consists of blocks, directed acyclic graphs have vertices and edges. Thus, crypto transactions are recorded as vertices. These transactions are then recorded on top of one another. Similar to a blockchain, however, transactions are also submitted to the DAG via nodes. Proof-of-work (PoW) tasks are required of nodes to submit a transaction. 

More info in https://cointelegraph.com/explained/what-is-a-directed-acyclic-graph-in-cryptocurrency-how-does-dag-work