How to Apply One Theme on Multiple WordPress Sites
If you want a consistent design across your entire WordPress network, you can apply one theme to multiple WordPress sites. For example, you may have a custom theme specially made for the main site in your network, with added features to display network-wide content. It may make sense for you to create a theme that is used on all sites within your network (other than your main site) that is created from the same design, with the same color scheme and graphics to provide that consistent look; if consistency and network branding is your goal.
When the network is enabled, available themes are shared among all sites. If a change to a theme file is made, every site in the network using that theme experiences the change because only one copy of the theme is being served. When a theme is enabled, it appears in the administrator’s Dashboard on the Manage Themes page (which you can access only if you are the administrator by clicking Dashboard→Appearance→Themes). Users can choose to activate this theme so it displays on the front side of the site. You must activate a theme for use across all sites in a network by clicking the Network Enable link under the Theme name in the Network Admin Dashboard (by clicking Network Admin and then clicking Themes).
The main network site could have 20 different themes installed in the main WordPress installation; however, if you have not enabled them for use across the entire network, then your site administrators will not see network-disabled themes in their Dashboards and therefore, will not be able to use them on their site.
If a consistent network design is what you’re after, you will run into a few troubles with the WordPress network because, by default, no matter what themes you have activated, the default WordPress Twenty Ten theme is the theme that gets activated whenever new sites are created within your network. It would be nice for WordPress to provide you with a global setting in the Network Admin Dashboard that would allow you to assign the default theme to every site that is created; however, that is currently not the case, unless you want to edit some code in the WordPress configuration file.
There is, however, a wonderful plugin that adds a simple item in the Network Admin Settings options called Default Theme. It gives you the option to assign a default theme to be the theme displayed on newly created sites.
The Default Theme plugin is not a free plugin, unfortunately; rather, it is available from the development group at WPMU Dev. To access the plugin, you do need to purchase membership to their site.
The WPMU Dev membership gives you access to hundreds of WordPress network-related plugins and themes for one annual membership. After you have your WPMU Dev membership; you can begin downloading any one of hundreds of plugins and themes for your WordPress network.

Blogging & Social Networking Glossary
archive
1. (noun) A list of previous blog posts, in chronological order. 2. (verb) To place files or blog posts in a safer place (on DVD or another server) for longer-term or backup storage.

Blogging & Social Networking Glossary
attribute
Used in an HTML tag to give an instruction to a Web browser. For example, in This link goes to <a href="http://www.google.com">Google</a>, the <a> tag gets an attribute (href) and a value ("http://www.google.com") to go along with the basic tag. In this case, the attribute indicates to the browser that what comes next is a hypertext reference — in this case, a Web page.

Blogging & Social Networking Glossary
blacklist
An often-centralized list of e-mail addresses, URLs, and IP addresses used by spammers that are then forbidden in any blog post on your blog. With an up-to-date blacklist, a lot of spam is stopped before it becomes a comment.

Blogging & Social Networking Glossary
block
To stop all contact with a MySpace user. He can’t comment on your blog page or send you any message that you actually receive.

Blogging & Social Networking Glossary
blog
A combination of the words Web and log. Bloggers (individuals, groups, or businesses) post a chronological log of information. Content is determined entirely by the author(s) of the blog; many are personal journals.

Blogging & Social Networking Glossary
blog post
An entry in a blog, possibly containing text, images, and other media.

Blogging & Social Networking Glossary
blogger
The author of a blog.

Blogging & Social Networking Glossary
blogging policy
Outlines what you’re allowed to post in your blog.

Blogging & Social Networking Glossary
blogging software
Technology that enables you to blog. Can be either hosted or nonhosted.

Blogging & Social Networking Glossary
blogroll
A collection of links used or recommended by a blogger.

Blogging & Social Networking Glossary
cookie
A short piece of computer code, stored on your computer, that enables Web sites to remember certain settings and information the next time you visit that site.

Blogging & Social Networking Glossary
Dashboard
A kind of control panel in Blogger that shows you the blogs you’ve set up, giving you access posting, using help resources, or even creating another blog.

Blogging & Social Networking Glossary
definition list
A type of HTML list that gives a term and then its definition and has built-in spacing to lay out those elements properly.

Blogging & Social Networking Glossary
disk space
Amount of room available on your hard drive.

Blogging & Social Networking Glossary
domain
A domain is the address, or main URL, that people type in the browser to get to your Web site. The domain name you choose can’t be used by anyone else.

Blogging & Social Networking Glossary
domain registrar
A service that enables you to register a domain name.

Blogging & Social Networking Glossary
entry
An single posting in a blog containing text, images, or other media, or any combination of those things.

Blogging & Social Networking Glossary
Facebook
A social-networking service that enables you to keep in contact with families and friends via the Web.

Blogging & Social Networking Glossary
Flickr
A Web site that allows you to share, organize, edit, and otherwise manage your photos.

Blogging & Social Networking Glossary
Friend List
Your virtual online address book in MySpace. You can become someone’s friend by either sending a fellow MySpacer a Friend Request or by being on the receiving end of a Friend Request from another MySpace user.

Blogging & Social Networking Glossary
hosted services
Manages the data, software, and Web hosting of a blog; the blogger just manages the content.

Blogging & Social Networking Glossary
HTML
The computer coding used by Web designers to create Web pages.

Blogging & Social Networking Glossary
hyperlink
A navigation tool that allows a user to go from one Web location to another by clicking. Hyperinks (or just links) are typically underlined.

Blogging & Social Networking Glossary
hypertext reference
In HTML, the address that a hyperlink connects to when clicked. For example, in This link goes to <a href="http://www.google.com">Google</a>, the hypertext reference (href) is http://www.google.com. Hyperlink references can also jump to new positions on the same page, open a new e-mail message, or begin a file download.

Blogging & Social Networking Glossary
link
Short for hyperlink, a navigation tool that allows a user to go from one Web location to another by clicking. Links are typically underlined.

Blogging & Social Networking Glossary
Mom test
A self-test that flags inappropriate blog posts. If you’d let your mom read the post, then it’s probably passed the Mom test. Specifically, don’t blog about topics you think will hurt others; don’t blog about others without their permission, even about topics you consider inconsequential; and don’t identify friends and lovers by name without their permission.

Blogging & Social Networking Glossary
MySpace
A social-networking service that enables you to keep in contact with families and friends via the Web.

Blogging & Social Networking Glossary
MySpace profile
Your MySpace identity. It can contain as much or as little information about you as you’d like.

Blogging & Social Networking Glossary
news aggregation
The ability to aggregate news by using RSS feeds. Having a news aggregator included with your blog package allows your site to pull in information from another blog.

Blogging & Social Networking Glossary
nonhosted service
Blog software that you set up on your own Web server. It allows you to take on all responsibilities related to maintaining your blog.

Blogging & Social Networking Glossary
ordered list
Contains items that must be listed in a particular order, such as a list of ranks or preferences. It may also indicate a list of steps for the reader to follow.

Blogging & Social Networking Glossary
pinging
An automated notification system for search engines and newsreaders, letting those services know that your blog has been updated. A ping occurs when one computer asks another whether it’s there; the second computer confirms its presence.

Blogging & Social Networking Glossary
post
1. (noun) An entry in a blog containing text, images, other media, or any combination of these. 2. (verb) The act of creating and/or uploading a blog entry.

Blogging & Social Networking Glossary
private profile
A MySpace profile that’s limited on who can view it, such as only people on your Friend List.

Blogging & Social Networking Glossary
public domain
The status of publications, processes, and product designs that are free from copyrights and/or patents and are available for anyone's use.

Blogging & Social Networking Glossary
social network
A service, such as Facebook or MySpace, that enables to keep in touch with people you know — and meet people you don’t know.

Blogging & Social Networking Glossary
spam
Unsolicited electronic messages sent in bulk that may be commercial, nonsensical, or malicious. In addition to e-mail spam, blog comments and blog forums can be targeted by spammers.

Blogging & Social Networking Glossary
tag
A relevant keyword associated or assigned to a piece of information, such as an image, a blog entry, or a video clip. Tags are usually chosen informally by the content creator or by the online community; they help give content to nontext media and organize information for ease of searching.

Blogging & Social Networking Glossary
Trackback
A technology that tracks references to a blog posting that occurs on other blogs. They allow bloggers to link to blog posts on related topics.

Blogging & Social Networking Glossary
transparent
1. Being honest and truthful on your blog. Also means that you admit mistakes and engage in dialogue with readers who leave comments. Considered proper blogging etiquette. 2. Integration of applications, programs, and media from different sources in such a way that the end user is unaware that the content is not self-contained.

Blogging & Social Networking Glossary
unordered list
unordered list is a series of bulleted items and is used for lists that don’t require numbering.

Blogging & Social Networking Glossary
video blog
A blog consisting of video files, or the practice of placing a video file in a blog post.

Blogging & Social Networking Glossary
video-sharing service
A service, such as YouTube, that enables you to share video with others.

Blogging & Social Networking Glossary
Web host
The Web server where you software, graphics, and other files live online.

Blogging & Social Networking Glossary
Web server
Technology that looks at what Web page is requested and then feeds the browser the appropriate file. It does most of the hard work of serving Web pages to visitors coming to your Web site.

Blogging & Social Networking Glossary
whitelist
A list of preselected users who are allowed to comment on your blog.

Blogging & Social Networking Glossary
YouTube
A video-sharing service.