Java is a high-level programming language that embraces object-oriented principles. It is inspired by the syntax and structure of C/C++, making it somewhat familiar to those who have worked with these languages.

Casting is the conversion of data of one type to another type either implicitly or explicitly.  

Casting happens for both primitive types and reference types. 

If the casting operation is safe, java will do automatic type casting. This is called implicit type casting. 

If java can't be sure whether the casting will be safe, java will not do automatic casting, but programmer can do the casting if he is sure about the outcome. This is called explicit type casting.

A programmer create software through a process called programming or coding. The purpose of programming is to develop an executable computer program that will automate performing a specific task or solving a given problem.

Programming involves activities such as analysis, design, generating algorithms and implementation of algorithms in a target programming language. These activities are also called as Software Development Lyfecycle (SDLC).

1. A compiler is a computer program that transforms source code written in a programming language into another computer language, often in a binary form, that is understood by the computer platform.

2. A compiler usually transforms a high-level programming language to machine code specific to a platform, so that it can then be directly executed in that platform.

The PATH environment variable contains a set of directories within the file system that the operating system uses to find executable files. When you type a command in command prompt, operating system will look for the corresponding executable in the current folder and then it will look inside every folder mentioned in the PATH environment variable in order.