Standrard streams are I/O communication channels between a program and its
executing environment. These days they serve as an abastraction to connect a 
program to its client unlike the old physical I/O (monitor/keyboard vs terminal)

There are three:
- Standard input (stdin) - Input data stream to program
- Standard output (stdout) - Output data stream from program
- Standard error (stderr) - Special output data stream from program (errors)

stdout exists seperately from stderr to solve the semi-predicate problem of 
multi valued returns.