The blockchain fee is a crypto transaction fee that is charged to users when performing transactions. The fee is collected in order to process the transaction on the network.
Every crypto transaction must be added to the Blockchain, in order to be considered successfully completed or valid. The work of validating transactions and adding them to the blockchain is done by miners, powerful computers that makeup and connect to the network.
Miners spend vast amounts of computing power and energy doing this for a financial reward: with every block added to the blockchain comes a bounty called a 'block reward', as well as all fees sent with the transactions that were included in the block.
For this reason, miners have a financial incentive to prioritise the validation of transactions that include a higher fee. Smaller transactions require less validation by miners, therefore incurring lower fees, while larger transactions require more validation by miners which incurs higher fees.
For someone looking to send funds and get a quick confirmation, the appropriate fee to include can vary greatly, depending on a number of factors. While the fee does not depend on the amount you’re sending, it does depend on network conditions at the time and the data size of your transaction.