PHP, which stands for "PHP: Hypertext Preprocessor" is a widely-used Open Source general-purpose scripting language that is especially suited for web development and can be embedded into HTML. Its syntax draws upon C, Java, and Perl, and is easy to learn.
The main goal of the language is to allow web developers to write dynamically generated web pages quickly, but you can do much more with PHP.
W3Techs reports that, as of January 2022, "PHP is used by 78.1% of all the websites whose server-side programming language we know."
PHP v8.0 is a major update of the PHP language. It contains many new features and optimizations including named arguments, union types, attributes, constructor property promotion, match expression, nullsafe operator, JIT, and improvements in the type system, error handling, and consistency.