Higher-order functions are functions that can take other functions as arguments or return functions as results. In Haskell, functions are treated as first-class citizens, which means they can be treated like any other value.

Here are some key characteristics and benefits of higher-order functions in Haskell:

1. Function Abstraction : Higher-order functions enable function abstraction by allowing you to write more general and reusable code. By accepting functions as arguments, higher-order functions can operate on a variety of behaviors and transformations, making them more flexible and adaptable.

2. Modularity and Composition : Higher-order functions facilitate modularity and composition by providing a way to combine and compose smaller functions into more complex computations. Functions can be composed using operators like `(.)` (dot), enabling a concise and declarative style of programming.

3. Code Reusability : Higher-order functions promote code reusability. By separating generic behavior from specific data or context, higher-order functions can be used with different arguments, making it easier to reuse the same functionality in different contexts or for different data types. 4. Encapsulation of Control Flow : Higher-order functions allow for encapsulating control flow patterns into reusable abstractions. Functions like `map`, `filter`, and `fold` are higher-order functions that abstract common control flow patterns, making it easier to express transformations and computations over collections of values.

5. Functional Combinators : Higher-order functions enable the creation of functional combinators, which are higher-level functions that combine and manipulate other functions. Combinators provide a vocabulary for expressing common patterns of computation concisely and declaratively.

6. Language Extension : Higher-order functions are essential for leveraging advanced features of the Haskell language, such as lazy evaluation, currying, and partial application. These features rely on the ability to pass and return functions, enabling powerful and elegant solutions to problems.

Examples of higher-order functions in Haskell include `map`, `filter`, `foldl`, `foldr`, and `zipWith`. These functions take other functions as arguments to perform operations on lists or other data structures. Higher-order functions provide a way to abstract and generalize computations, leading to more modular and reusable code.