The typedef keyword is used to allow user defined data types based on existing data types to be defined.
Thus enabling a user created alias for an existing data type to be defined.
The syntax is:
typedef existing_type new_type ;
typedef long int spokes ;
The above shows that a new datatype called spokes has been defined as being equivalent to a long int, and the two could thereon be used interchangeably within the program it was defined in.
spokes myVar ; is equivalent to long int myVar ;