A web app, or web application, is a computer program that runs in a web browser. It is accessed over the internet and typically provides a user interface for interacting with the application's functionality. Web apps can range from simple websites that display information, to complex applications that allow users to perform advanced tasks, such as online shopping, social networking, or productivity tools.

Web apps can be written in a variety of programming languages, including JavaScript, HTML, and CSS, and often use server-side scripting languages such as PHP, Python, or Ruby. They can be hosted on a web server and accessed through a web browser on any device with an internet connection.

Web apps have become increasingly popular due to their accessibility and ease of use, as users can access the app from anywhere with an internet connection, without the need to install software on their device. Additionally, web apps can be updated more easily than traditional desktop applications, as updates are made on the server and immediately available to all users.

Web apps can be developed for a variety of purposes, from providing simple informational content to more complex functionalities like online shopping, project management, and collaboration tools. Some examples of web apps include:

1. Social media platforms like Facebook, Twitter, and Instagram.
2. Productivity tools like Google Docs, Trello, and Asana.
3. E-commerce websites like Amazon, eBay, and Etsy.
4. Online banking and financial management platforms like Mint and PayPal.
5. Video conferencing tools like Zoom and Skype.
6. Learning management systems like Moodle and Blackboard.

1. Web apps can be accessed from a variety of devices, including desktop computers, laptops, tablets, and smartphones, making them incredibly versatile and accessible. They are also often developed with responsive design techniques, which means that they can adapt to the size and shape of the device screen they are being viewed on, ensuring a consistent user experience across all devices.

1. Developing web apps involves a range of skills and technologies, including front-end web development (HTML, CSS, and JavaScript), back-end development (server-side scripting languages like PHP or Python), database management, and web security. Many modern web apps also utilize APIs (Application Programming Interfaces) to connect with other services and systems, allowing for seamless integration with other software and services.