By default, the .php extension will show in a web browsers address bar. For example, if you've a page named About.php, the address bar will show www.example.com/About.php.

Ensure the rewrite module is enabled. If rewrite_module is in the list of modules of the following command, then the rewrite_module is enabled.

[root@server1 ~]# httpd -M
. . .
rewrite_module (shared)

In the /etc/httpd/conf/httpd.conf file, inside of <Directory /var/www>, ensure AllowOverride is set to All.

<Directory /var/www>
. . .
AllowOverride All

The ps command can be used to determine if your system is using init or systemd. If PID 1 is init, then you will use the service command. If PID 1 is systemd, then you will use the systemctl command.

If your system is using systemd, use the systemctl command to restart httpd.

systemctl restart httpd

If your system is using init, use the service command to restart httpd.

service httpd restart

Use the apachectl configtest command can be used to verify the configuaration of HTTPD is OK.

[root@server1 ~]# apachectl configtest
. . .
Syntax OK

Create the .htaccess file.

[root@server1 ~]# touch /var/www/html/.htaccess

Edit the .htaccess file, and add the following.

RewriteEngine On
RewriteRule ^about$ about.php [NC]

Now, .php will no longer be displayed.