It would depend on how you are sending the data. I mean, for example, if you use UART to communicate, it has a buffer to hold received characters and a buffer to transmit data. You can check Universal asynchronous receiver/transmitter to learn more about how UART works.
Most of the communication interfaces have a similar behaviors but how work differs from case to case. In order to give a more accurate answer I would need to know how you'd like to send data.