Transaction fees are included with your bitcoin transaction in order to have your transaction processed by a miner and confirmed by the Bitcoin network.
The space available for transactions in a block is currently artificially limited to 1 MB. This means that to get your transaction processed quickly you will have to outbid other users.
This site keeps a record of how Bitcoin transaction fees evolve over time.
The fees shown at the historic charts and tables are in US dollars per transaction and in satoshis per byte.
We also show the latest fee estimate in US Dollars/transaction in the list below. To calculate the fees per transaction.