It’s important to note the description of the function before using it.

(from php.net)
is_int: Find whether the type of a variable is integer
is_numeric: Finds whether a variable is a number or a numeric string

PHP is a loosely typed language. It doesn’t enforce typing, but it does keep track of types to a degree. Since it’s loosely typed, you can usually avoid functions that talk about the *type* of a variable. For example, is_int helps you probe the *type* of a variable, which is very different from the *contents* of the variable (even in a loosely typed language like PHP).

is_numeric is concerned with the *contents* of the variable, not the type. It tells you if the variable is a number (123) or a numeric string (“123”).