Nucleus CMS is one of the many open-source blog management software package written in PHP, with a MySQL database backend, primarily written and maintained by Wouter Demuynck.

Nucleus is lightweight, flexible, and secure.Nucleus is a real multi-blogging, multi language platform. It can maintain multiple blogs - in one admin, aech blog has different templates, users, languages, etc. It can run on your own server. It has the ability to make draft posts (publish for later), and schedule posts (future posts). It is a modular platform - extensible via many free and paid plugins.

Due to the popularity of wordpress as the most used blogging platform, many has overlooked the power of Nucleus. I have tried nucleus myself - and it's the only one multi-blogging platform I know.

The latest version was released last March 16, 2009. Please see Nucleus v3.41 Released.

The design of Nucleus-generated sites is managed by the combination of skins & templates. Skins for nucleus are free. Anyone can download from here: Nucleus Skins.

Templates, themes, or skins, control the always changing parts of the weblog that appear on these different pages. These work together to offer you maximum flexibility, and (once you understand the concept) are very ease to manage.

* The skins controls the different pages that are part of a weblog. These mainly include the static parts of your site (e.g. the header, site navigation & copyright disclaimer that surround the articles you post). A skin consists of 8 different skinparts. Each of those controls a different kind of webpage served up by Nucleus:

1. Main Index skinpart - manages the front page of your weblog
2. Item Pages skinpart - the look of individual item pages
3. Archive List skinpart - displays an overview of archived blog pages (default is per month).
4. Archive skinpart - controls the display of the monthly archive pages are displayed
5. Member Details skinpart - is used to show information about blog members, and a mailform so visitors can contact them
6. Search skinpart - controls the look of the search results pages
7. Errors skinpart - enables you to customize the Nucleus error page
8. Image popups skinpart - when adding images to a post, you can choose if they should be displayed inline or as pop-up. Image pop-ups are controlled by this skinpart.

* The templates control the formatting of dynamic parts of weblog pages. These dynamic parts are things like individual articles (or posts), archive listings, and comments. These are included in the skins as separate blocks of content. For a complete site, there are always two different templates:
1. Default template (default/index) - most often used to format articles and other blocks of content of the front page and in the archives.
2. Detailed template (default/item) - always needed to display a selected article or post on an item page.
* Extra: modern web designers separate appearance from information, context from content. This can be achieved by putting all design declarations into a stylesheet, a .css file, and linking the different pages of a site to that file. An example of that method is the default Nucleus design. This setup has many advantages, for instance: you can change the design of the entire site by editing just the stylesheet. If you are interested in learning more about this subject, read Westciv.com's Guide to how stylesheets work.