Newbie programmer question: How do parsers work?(Python examples?)

[faulkner]

http://pages.cpsc.ucalgary.ca/~aycock/spark/
http://www-128.ibm.com/developerworks/library/l-spark.html

bio_enthusiast wrote:
> I was wondering exactly how you create a parser. I'm learning
> Python and I recently have come across this material. I'm interested
> in the method or art of writing a parser.
>
> If anyone has some python code to post for an abstract parser, or links
> to some informative tutorials, that would be great.