A computer "speaks" in binary, or a series of 1's and 0's. However, they don't actually recognize these numbers like we can recognize numbers and letters, but instead, the 1's and 0's represent power. 1 represents on and 0 represents off. Each 1 or 0 is a bit. Every 8 bits becomes 1 byte. Each byte represents data storage capacity. When writing a program, the programming language needs to be translated into binary, so that the computer can understand it:
Input (Source Code)
Process (depends on the language)
Output (Object Code)
Java Compiler - entire program 0,1
Pascal Interpreter - line by line binary code
etc.