Regular Expression - A cosmic way to search or match String

Regular Expression is the most powerful expression language to search string or match string sequences. It easy to use when it found already integrated with some language.
But, What the logic behind it? How regular expression make sure to search exact string? How does we can implement our own regular expression parser?

These type of question make a programmer to think. Thus, the objective of this post:

1. Figure out the parsing technique.

2. An example with Java Programming Language.

3. Figure out the parsing implementation in Java.

4. Make your own parser in C/C++ Languages.

5. Conclusion.