How to Use WordPress Templates
WordPress offers four main templates to create your own theme. You can also edit the template tags in the theme you're currently using. Those four main templates are Header, Main Index, Sidebar, and Footer.
The Header template
The Header template for your WordPress themes is the starting point for every WordPress theme because it tells Web browsers information such as the title and URL of your blog.
You can use the bloginfo(); tag plus a little HTML code to display your blog name and tagline. Most blogs have a clickable title, which is a site title that takes you back to the main page when it's clicked.
The Main Index template
The Main Index template drags your blog posts out of the MySQL database and inserts them into your blog. The filename of the Main Index template is index.php. The first template tag in the Main Index template calls in the Header template, meaning that it pulls the information from the Header template into the Main Index template.
Your theme can work without calling in the Header template, but it'll be missing several essential pieces. Without the call to the Header template, your blog resembles this image:
The Sidebar template
The filename of the Sidebar template is sidebar.php. Typically, the sidebar appears on the right or left side of your WordPress template. In the default Twenty Ten theme, the sidebar is displayed on the right side of the template, by default:
Similarly to the Header template, the Sidebar template is called into the Main Index template.
The Footer template
The filename of the Footer template is footer.php. Usually, the footer sits at the bottom of the page and contains brief information about the site, such as copyright statements and credits to the theme designer or hosting company.
Similarly to the Header and Sidebar templates, the Footer template gets called into the Main Index template.
Other templates
Some other (optional) templates include
Comments template (comments.php): You need the Comments template if you plan to host comments on your blog; it provides all the template tags you need to display those comments.
Single Post template (single.php): When your visitors click the title or permalink of a post you've published to your blog, they're taken to that post's individual page.
Page template (page.php): You can use a Page template for static pages.
Search Results (search.php): When someone uses the search feature to search your site for specific keywords, this template formats the return of those results.
404 template (404.php): Use this template to create a custom 404 error page, which is the page visitors get when the browser can't find the page requested.

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.

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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.

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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.