A callback is a function passed as an argument to another function to be executed later within that outer function. It essentially allows one function to call another function to perform certain actions when a specific condition is met or an event occurs.
Callbacks are prevalent in programming, especially in languages that treat functions as first-class citizens, allowing functions to be passed as arguments to other functions.
They are often used in event handling systems, such as web development or working with user interfaces. A common example is the use of callbacks in JavaScript to respond to user interactions on a webpage, like when a button is clicked or when a resource has finished loading.
Asynchronous programming refers to the design and implementation of programs that utilize asynchronous operations to execute tasks independently of one another. This involves starting operations without waiting for their completion, allowing the program to perform other tasks in the meantime.
This programming approach is particularly useful for operations that take time, such as reading data from a remote source, writing to a file, or fetching information from the internet. Instead of blocking the main flow of the program and waiting for the results of these tasks, asynchronous programs can carry out other activities while waiting for these time-consuming tasks to finish.
Asynchronous programming is often employed in situations where parallelism, responsiveness, and efficiency are crucial. Different programming languages and environments offer various techniques to implement asynchronous programming, such as callbacks, promises, Async/Await, or specific libraries and frameworks designed to facilitate and manage asynchronous operations.