sajad torkamani

Add PPA repository

Ubuntu's default PPA repositories will probably not include the latest PHP version so you'll want to add ppa:ondrej/php.

sudo add-apt-repository ppa:ondrej/php
sudo apt-get update

Install PHP packages

Head over to the PHP website to check the current stable version. At the time of writing, this is 8.1.1.

Assuming we'll use PHP with Nginx and MySQL, we'll want to install two packages.

sudo apt install php8.1-fpm php8.1-mysql

These two packages will download other core PHP packages as their dependencies.

Verify installation

php -v

This should output something like:

PHP 8.1.1 (cli) (built: Dec 31 2021 07:26:20) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.1.1, Copyright (c) Zend Technologies
    with Zend OPcache v8.1.1, Copyright (c), by Zend Technologies

Sources