I think it is a very use full link and just thought to dump it in my blog..
- Regular Expressions
Explains the concept of regular expressions.
- Early Beginnings
Explains the history of regular expressions.
- Uses for Regular Expressions
Illustrates circumstances that would benefit from the use of regular expressions.
- Regular Expression Syntax
Demonstrates the elements that comprise the regular expression syntax.
- Build a Regular Expression
Explains how you combine elements to produce a regular expression.
- Order of Precedence
Lists the operators and the order in which they are evaluated in a regular expression.
- Ordinary Characters
Explains the concept of ordinary characters that apply to regular expressions.
- Special Characters
Explains the concept of special characters that apply to regular expressions.
- Non-Printable Characters
Lists the non-printing characters that apply to regular expressions.
- Character Matching
Explains how special characters match printing or non-printing characters in regular expressions.
Lists the quantifier characters and explains how to use them in regular expressions.
Explains the concept of anchors which allow you to fix a regular expression to either the beginning or end of a line.
- Alternation and Grouping
Explains how to use the '|' character for choices between to alternatives and how grouping effect the outcome of expressions.
Provides information about how you can store part of a matched pattern for later use.