Nginx (pronounced "engine-x") is a high-performance, open-source web server and reverse proxy server software. It is designed to handle and efficiently serve static and dynamic content on the web. Nginx is known for its scalability, speed, and ability to handle high levels of concurrent connections.

To install Nginx on Ubuntu, you can follow these steps:

1. Update the package list to ensure you have the latest package versions:

   sudo apt update

2. Install Nginx by running the following command:

   sudo apt install nginx

3. During the installation process, you may be prompted to confirm the installation. Type 'Y' and press Enter to proceed.

4. Once the installation is complete, Nginx will start automatically. You can verify the status of the Nginx service by running:

   sudo systemctl status nginx

   If the service is running, you should see output indicating that it is active and running.

5. By default, Nginx will create a basic configuration file. You can open a web browser and enter your server's IP address in the address bar to confirm that Nginx is working. You should see a "Welcome to Nginx" page.

   Note: If you are using a firewall, make sure to allow HTTP (port 80) and HTTPS (port 443) traffic to access your server.

   Congratulations! You have successfully installed Nginx on your Ubuntu server. You can now start configuring Nginx to serve your websites or applications. The Nginx configuration files are typically located in the /etc/nginx directory.