API stands for Application Programming Interface.
This API is a set of functions and routines provided to you, the programmer
and user, to make the use of the serial I/O board easy, reliable, and consistent.
Although you could communicate with the board using low-level serial port functions
supported by your particular programming language,
the API provides a more intuitive method. When using the API, the programmer does
not need to know much about how the serial I/O board works nor how
to perform low-level serial communications. Because the
programmer doesn't need to keep track of numerous details, the API helps
to avoid frustrating mistakes and bugs. Another benefit of using an API is that it
encourages consistency in programming. Common tasks will always be handled in a similar
fashion, making programs easier to understand and maintain.