What is a Web App

Web applications are a critical component of the internet, providing an interface for users to interact with web servers and databases. They are built using languages such as HTML, CSS, JavaScript, and often involve server-side scripting languages like PHP, Python, or Ruby. Web applications can range from simple static web pages to complex dynamic platforms that allow users to perform tasks, interact with data, and connect with other users.

How Web Apps Work

Web applications follow a client-server model. The client (usually a web browser) sends a request to the server, which processes the request and returns a response. This response is typically a web page that the browser renders for the user to interact with. The server-side processing can involve querying a database, performing calculations, or other complex tasks. The result is then sent back to the client as HTML, CSS, and JavaScript, which the browser interprets to display the web page.

Architecture

Web applications typically have a three-tier architecture. The presentation tier is the user interface and communicates with the other tiers. The application tier (also known as the logic tier) processes commands, makes logical decisions and evaluations, and performs calculations. It also moves and processes data between the two other tiers. The data tier includes databases or other data sources. This architecture allows for separation of concerns, where each tier can be developed and maintained independently.

Security

Web applications are often a target for hackers because they provide access to backend data. Common web application vulnerabilities include SQL injection, cross-site scripting (XSS), and cross-site request forgery (CSRF). Ethical hackers need to understand these vulnerabilities to protect web applications effectively. Additionally, web applications should implement security measures such as data encryption, user authentication, and secure coding practices to protect against these threats.