Python is a computer programming language often used to build websites and software, automate tasks, and analyze data. Python is a general-purpose language, not specialized for any specific problems, and used to create various programmes.

A React JS training introduces you to the "React" JavaScript library, which allows developers to build dynamic and interactive user interfaces for web applications by creating reusable components, making it a powerful tool for building complex front-ends, particularly for single-page applications (SPAs), with a focus on performance and maintainability; developed and maintained by Facebook, React utilizes a "virtual DOM" for efficient updates to the user interface. 

PHP is the most popular scripting language for web development. It is free, open source and server-side (the code is executed on the server). MySQL is a Relational Database Management System (RDBMS) that uses Structured Query Language (SQL). It is also free and open source.

".NET training" is an educational program that teaches individuals how to develop software applications using Microsoft's .NET framework, a versatile platform allowing for the creation of various types of applications like web, desktop, and mobile apps, primarily utilizing languages like C# to build robust and scalable software across different operating systems.