different data types are used for different types of data.
a string is used for text
an int is used for a whole number (so no decimal point)
the reason why there are different data types mostly has to do with available memory. in int is “cheaper” (costs less processing power and memory) than a float.
nowadays it doesn’t matter that much for modern computers or even phones, but when you are working embedded (hardware programming) every tick (processing power unit) is important
char is a singles character e.g 'A'
int is a whole number
float is a number with a decimal point
double is a number with a decimal point but can hold a larger number than float.
Use the <limits.h> and <float.h> to find the upper and lower limits, here's an example for an int:-
printf("%d \n", INT_MAX);
printf("%d \n", INT_MIN);