What exactly causes a bitcoin transaction to confirm
thats something I thought I knew but this thread makes me question myself. I understood that you where queued with other transactions to fill an order, but it is the mining that validates the transaction, or the buying and selling of bitcoins on the network? OR is it more in depth to due with the mining process?
It is the mining that "confirms" the transaction. "A confirmation" simply means that the transaction was included in a block. "Multiple confirmations" simply means that more blocks were added to the blockchain after the block that includes the transaction (those additional blocks don't also include the transaction, they just come after the one block that has the transaction).
"Validating" a transaction is a bit different than "confirming" a transaction. Every peer on the network validates that every transaction they receive is "valid" before they bother to relay it to any other peers. If you try to construct an "invalid" transaction, it won't get any further than the computer you use to try to transmit it.
Confirming a transaction adds security to the transaction. It makes it significantly more difficult for an attacker to reverse (or more specifically double-spend the inputs of) a transaction that they send to you. The more blocks that get added to the blockchain after your transaction is in there, the more difficult it is to modify that portion of the blockchain and alter the transaction that you received.
There is a pool of unconfirmed transactions. Each miner (or mining pool) is allowed to use any method they like to choose which of those unconfirmed transactions to include in the block they are mining. Since the miners (or mining pools) receive the transaction fees of the transactions that they include (the transactions that they "confirm"), they have a financial incentive to choose the transactions that have voluntarily included a fee. As a matter of fact they have a financial incentive to choose the transactions that have the highest fee per byte of transaction size.
The block has a maximum size. If there are not enough fee-paying transactions to fill the block, most miners (or mining pools) will fill some of the excess space with some free transactions. Most of them recognize that it is in their long term benefit to increase the popularity and usability of bitcoin. However, they will obviously prioritize transactions with fees to increase their profits when possible.
As such, you drastically increase the likelihood that your transaction will be included in one of the next few blocks if you include a small fee.