MediaWiki doesn't include regular features found in corporate CMSes, like a publication workflow or access control lists, but does offer a variety of tools to handle spam and vandalism.
Because it was an experiment, Wikipedia was originally powered by UseModWiki, an existing GPL wiki engine written in Perl, using CamelCase and storing all pages in individual text files with no history of changes made.
It soon appeared that CamelCase wasn't really appropriate for naming encyclopedia articles
In late January 2001, UseModWiki developer and Wikipedia participant Clifford Adams added a new feature to UseModWiki: free links; i.e., the ability to link to pages with a special syntax (double square brackets), instead of automatic CamelCase linking. A few weeks later, Wikipedia upgraded to the new version of UseModWiki supporting free links, and enabled them.
In 2001, performance was already an issue, notably because UseModWiki stored its content in a flat file database
In 2002, Lee Daniel Crocker rewrote the code again, calling the new software "Phase III"
reorganized the existing architecture for better performance and hacked all the code". Profiling features were added to track down slow functions.
in November 2002, administrators had to temporarily disable the "view count" and "site" statistics which were causing two database writes on every page view.
2003, developers discussed whether they should properly re-engineer and re-architect the software from scratch, before the fire-fighting became unmanageable, or continue to tweak and improve the existing code base. They chose the latter solution, mostly because most developers were sufficiently happy with the code base, and confident enough that further iterative improvements would be enough to keep up with the growth of the site.