PHP
PHP is a widely-used open-source server-side scripting language designed for web development, originally created in 1994. It is embedded in HTML and executed on the server to generate dynamic web pages, handle forms, manage databases, and create session tracking. While often associated with legacy systems, it remains a foundational technology for many websites and applications, particularly those built with older frameworks like CodeIgniter or custom scripts.
Developers should learn PHP to maintain and modernize legacy web applications, as it powers a significant portion of the internet, including content management systems like WordPress and Drupal. It is essential for roles involving backend development, server-side logic, and database interactions in older systems, and understanding PHP helps in migrating or integrating with newer technologies while preserving existing functionality.