Data types in C: bool, char, double, float, int, long, string

bool  (true or false)
char  (a single character, not two or more)
int   (an integer; it has a certain size; you can only count up to a certain size number with int, typically
         4 billion)
float   (floating point number, which is a fancy way of saying a real number [something that has a
            decimal point])
double   (just a real number that can have even more digits after the decimal point)
long   (uses more bits so can count higher than int; companies like Facebook and Google have more
           data than 4 billion, so they may need these types of numbers)
string   (one or more characters inside double quotes " " )
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[source: harvard, cs50, david malan]