Here I am giving a step by step example to install PHP 7.3 on Windows 10. But before installing PHP you should install Apache Web Server and to know how to install Apache Web Server on Windows 10, please check the following link Install Apache on Windows 10.
Steps to Install PHP 7.3 on Windows 10 PC
Click on the following link to download PHP 7.3 for Windows and choose the VC15 x64 Thread Safe or VC15 x86 Thread Safe version.
Now extract the ZIP file to a folder, for example, F:\php73.
Open the folder F:\php73 and locate the file php.ini-development and rename it to php.ini.
In the php.ini file, find and modify the extension_dir and set as the following: (Note: change the folder name to your PHP installation folder)
extension_dir = "F:/php73/ext"
Uncomment the following lines to enable.
extension=curl extension=gd2 extension=mbstring extension=mysql extension=pdo_mysql extension=xmlrpc
Add F:\php73 to the PATH variable in Windows by clicking on the My Computer > Properties > Advanced System Settings > Environment Variables as shown in the below image:
Configure Apache Web Server for PHP 7.3
Open the CONF folder in Apache Web Server installation folder and open the httpd.conf file. Then find and modify the DirectoryIndex as shown below:
DirectoryIndex index.php index.html
Add the following lines to the httpd.conf file:
PHPIniDir "F:/php73" AddHandler application/x-httpd-php .php LoadModule php7_module "F:/php73/php7apache2_4.dll"
Now restart the Apache server and test the PHP file. Create a PHP file and add the following line and save it as index.php in the htdocs folder in Apache installation directory.
<?php phpinfo(); ?>
Now double click the file to test. The output is as shown in the featured image of this article.