Closures, also known as first-class functions, are an interesting language feature that emerged from lambda calculus in the 1930s. The basic idea is that a function is also a value that can be passed around to other functions as a parameter. These types of functions are called closures, but there is really no difference between a function and a closure.
Closures can be saved to variables and used as parameters for other functions. They are even written inline when consuming a function that expects a closure as a property.
