SEO READING ROOM

Simple-to-understand URLs will convey content information easily

Creating descriptive categories and filenames for the documents on your website can not only help you keep your site better organized, but it could also lead to better crawling of your documents by search engines. Also, it can create easier, "friendlier" URLs for those that want to link to your content. Visitors may be intimidated by extremely long and cryptic URLs that contain few recognizable words.
URLs like (1) can be confusing and unfriendly. Users would have a hard time reciting the URL from memory or creating a link to it. Also, users may believe that a portion of the URL is unnecessary, especially if the URL shows many unrecognizable parameters. They might leave off a part, breaking the link.
Some users might link to your page using the URL of that page as the anchor text. If your URL contains relevant words, this provides users and search engines with more information about the page than an ID or oddly named parameter would (2).

Use unique descriptions for each page

Use unique descriptions for each page using a single description meta tag across all of your site's pages or a large group of pages
Avoid:
Having a different description meta tag for each page helps both users and Google, especially in searches where users may bring up multiple pages on your domain (e.g. searches using the site: operator). If your site has thousands or even millions of pages, hand-crafting description meta tags probably isn't feasible. In this case, you could automatically generate description meta tags based on each page's content.

Use description meta tags to provide both search engines and users with a summary of what your page is about!

Accurately summarize the page's content

Write a description that would both inform and interest users if they saw your description meta tag as a snippet in a search result.

Avoid:
writing a description meta tag that has no relation to the content on the page using generic descriptions like "This is a web page" or "Page about baseball cards" filling the description with only keywords copying and pasting the entire content of the document into the description meta tag

What are the merits of description meta tags?

Description meta tags are important because Google might use them as snippets for your pages. Note that we say "might" because Google may choose to use a relevant section of your page's visible text if it does a good job of matching up with a user's query. Alternatively, Google might use your site's description in the Open Directory Project if your site is listed there (learn how to prevent search engines from displaying ODP data). Adding description meta tags to each of your pages is always a good practice in case Google cannot find a good selection of text to use in the snippet. The Webmaster Central Blog has an informative post on improving snippets with better description meta tags.
Words in the snippet are bolded when they appear in the user's query (2). This gives the user clues about whether the content on the page matches with what he or she is looking for. (3) is another example, this time showing a snippet from a description meta tag on a deeper page (which ideally has its own unique description meta tag) containing an article.

(3) A user performs the query [rarest baseball cards]. One of our deeper pages, with its unique description meta tag used as the snippet, appears as a result.

Description Meta Tag

Summaries can be defined for each page:
A page's description meta tag gives Google and other search engines a summary of what the page is about (1). Whereas a page's title may be a few words or a phrase, a page's description meta tag might be a sentence or two or a short paragraph. Google Webmaster Tools provides a handy content analysis section that'll tell you about any description meta tags that are either too short, long, or duplicated too many times (the same information is also shown for <title> tags). Like the <title> tag, the description meta tag is placed within the <head> tag of your HTML document.

<html>
<head>
<title>Brandon's Baseball Cards - Buy Cards, Baseball News, Card Prices</title>
<meta name="description=" content="Brandon's Baseball Cards provides a large selection of vintage and modern baseball cards for sale. We also offer daily baseball news and events in">
</head>
<body>

(1) The beginning of the description meta tag for our homepage, which gives a brief overview of the site's offerings.

Best Practices

Accurately describe the page's content choosing a title that has no relation to the content on the page using default or vague titles like "Untitled" or "New Page 1"
Avoid:
Create unique title tags for each page
Each of your pages should ideally have a unique title tag, which helps Google know how the page is distinct from the others on your site. using a single title tag across all of your site's pages or a large group of pages
Avoid:
Use brief, but descriptive titles
Titles can be both short and informative. If the title is too long, Google will show only a portion of it in the search result.
Avoid:
using extremely lengthy titles that are unhelpful to users stuffing unneeded keywords in your title tags

Page titles are an important aspect of search engine optimization.

Links:
The anatomy of a search result
http://googlewebmastercentral.blogspot.com/2007/11/anatomy-of-search-result.html Diagram of a Google search results page
http://www.google.com/support/websearch/bin/answer.py?answer=35891

Page title contents are displayed in search results

If your document appears in a search results page, the contents of the title tag will usually appear in the first line of the results (if you're unfamiliar with the different parts of a Google search result, you might want to check out the anatomy of a search result video by Google engineer Matt Cutts, and this helpful diagram of a Google search results page). Words in the title are bolded if they appear in the user's search query. This can help users recognize if the page is likely to be relevant to their search (2).

(2) A user performs the query [baseball cards]. Our homepage shows up as a result, with the title listed on the first line (notice that the query terms the user searched for appear in bold).

The title for your homepage can list the name of your website/business and could include other bits of important information like the physical location of the business or maybe a few of its main focuses or offerings (3).

If the user clicks the result and visits the page, the page's title will appear at the top of the browser.

(3) A user performs the query [rarest baseball cards]. A relevant, deeper page (its title is unique to the content of the page) on our site appears as a result.

Indicate page titles by using title tags

A title tag tells both users and search engines what the topic of a particular page is. The <title> tag should be placed within the <head> tag of the HTML document (1). Ideally, you should create a unique title for each page on your site.

<html>
<head>
<title>Brandon's Baseball Cards - Buy Cards, Baseball News, Card Prices</title>
<meta name="description=" content="Brandon's Baseball Cards provides a large selection of vintage and modern baseball cards for sale. We also offer daily baseball news and events in">
</head>
<body>

Search Engine Optimization Starter Guide

An example may help our explanations, so we've created a fictitious website to follow throughout the guide. For each topic, we've fleshed out enough information about the site to illustrate the point being covered. Here's some background information about the site we'll use:

Website/business name: "Brandon's Baseball Cards"
Domain name: brandonsbaseballcards.com
Focus: Online-only baseball card sales, price guides, articles, and news content
Size: Small, ~250 pages

Search engine optimization affects only organic search results, not paid or "sponsored" results such as Google AdWords.