PHP is an open source server-side scripting language used to develop dynamic web pages. It allows computational and server/database programming in web pages, enabling tasks like storing user-entered form data in a database. Dynamic web pages can change content based on events like displaying the current weather of a user's city. PHP syntax is based on C and supports object-oriented programming. It is commonly used for server-side scripting but can also be used for command line scripting and desktop applications. PHP training in Chandigarh can be obtained from CBITSS, which provides PHP courses to help students learn PHP and build careers with it.