App development is the process of creating software applications that run on various devices, such as smartphones, tablets, and digital assistants. App development can be done for different operating systems, such as Android and iOS, or for multiple platforms using cross-platform frameworks. App development can also be done for different purposes, such as entertainment, education, business, or social networking.

App development involves using various tools and techniques to design, code, test, and deploy the software applications. Some of the common tools and techniques used for app development are:

Programming and markup languages - these are the languages that define the logic, structure, and appearance of the applications. Some of the popular languages used for app development are Java, Swift, C#, Python, HTML5, CSS3, and JavaScript.

Development environments - these are the workspaces where developers can write and edit code, debug errors, and run simulations. Some of the popular development environments used for app development are Android Studio, Xcode, Visual Studio Code, Eclipse, and IntelliJ IDEA.

Frameworks and libraries - these are collections of pre-written code that provide common functionality and features for the applications. Some of the popular frameworks and libraries used for app development are Flutter, Kotlin, React Native, Ionic, Xamarin, Firebase, and TensorFlow.

Testing tools - these are tools that help developers check the quality, performance, and functionality of the applications. Some of the popular testing tools used for app development are Espresso, XCTest, Appium, Selenium, JUnit, and Mocha.

Distribution platforms - these are platforms that help developers publish and distribute their applications to the users. Some of the popular distribution platforms used for app development are Google Play Store, Apple App Store, Amazon Appstore, and Microsoft Store.