This article covers how to install an Apache web server on your Debian 9 server. The Apache HTTP server is the most widely-used web server in the world. It provides many powerful features including dynamically loadable modules, robust media support, and extensive integration with other popular software.How to Install Apache ?1. Let's begin by updating the local package index to reflect the latest upstream changes:$ sudo apt update2. Then, install the apache2 package:$ sudo apt install apache2 After confirming the installation, apt will install Apache and all required dependencies.The Apache profiles begin with WWW:1. WWW: This profile opens only port 80 (normal, unencrypted web traffic).2. WWW Cache: This profile opens only port 8080 (sometimes used for caching and web proxies).3. WWW Full: This profile opens both port 80 (normal, unencrypted web traffic) and port 443 (TLS/SSL encrypted traffic).4. WWW Secure: This profile opens only port 443 (TLS/SSL encrypted traffic).How to Manage Apache Process ?To stop your web server, type:$ sudo systemctl stop apache2To start the web server when it is stopped, type:$ sudo systemctl start apache2To stop and then start the service again, type:$ sudo systemctl restart apache2If you are simply making configuration changes, Apache can often reload without dropping connections. To do this, use this command:$ sudo systemctl reload apache2By default, Apache is configured to start automatically when the server boots. If this is not what you want, disable this behavior by typing:$ sudo systemctl disable apache2To re-enable the service to start up at boot, type:$ sudo systemctl enable apache2Apache should now start automatically when the server boots again.