FAQ: 搜索引擎优化技巧

日期:2005-04-23   来源: sitepoint   作者: stymiee
FAQ: Search Engine Optimization

This thread/post is design to help answer the most common questions here and also to help spark some debate. The answers below are not perfect nor do I claim they are. I'm hoping for feedback to help make this more complete and accurate so please feel free to point out any mistakes, omissions, or otherwise. If I missed a question you feel is common, let me know so I can add it here.

(Since SEO is not a science this is a gutsy post to make so cut me some slack! )

What are SERPs?

SERPs is an anacronym for Search Engine Results Pages. Basically they are the search results you receive when doing a search at a search engine.


What is PR?

PR stands for PageRank. As explained by Google:
Quote:
PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page's value. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at more than the sheer volume of votes, or links a page receives; it also analyzes the page that casts the vote. Votes cast by pages that are themselves "important" weigh more heavily and help to make other pages "important."

Important, high-quality sites receive a higher PageRank, which Google remembers each time it conducts a search. Of course, important pages mean nothing to you if they don't match your query. So, Google combines PageRank with sophisticated text-matching techniques to find pages that are both important and relevant to your search. Google goes far beyond the number of times a term appears on a page and examines all aspects of the page's content (and the content of the pages linking to it) to determine if it's a good match for your query.


Summary: PageRank is your page's popularity on the Web. (Notice I didn't say website).


How do I find out what my PR is?

There are many different ways to do this:

Websites that check for you:

http://www.digitalpoint.com/
http://www.pagerank.net/
http://www.webmasterbrain.com/upcom...ool--tool11.htm
http://www.webmasterbrain.com/prog/
http://www.stargeek.com/pr_checker.php
http://www.prlookup.com/

Software:

Google Toolbar: http://toolbar.google.com/
PageRank FireFox Extension: http://pagerankstatus.mozdev.org/installation.html


How do I increase my PageRank?

Since PageRank is an indicator of a page's link popularity it should be obvious how to increase your PageRank - GET MORE INCOMMING LINKS! High PR links are ideal but don't underestimate the power of low PR links. Afterall, PR does add up.


What is anchor text? Why is it important?

Anchor text is the visible hyperlinked text on the page. For example, let's examine this code:

<a href="http://www.sitepoint.com/forums/">Webmaster Forums</a>

The anchor text for this link is "Webmaster Forums". This is important in search engine rankings because the search engines use anchor text to help determine the relevance of a page being linked to for those keywords. By having this link pointing to their forum's web page, SitePoint Forums will perform better in searches for the phrase "webmaster forums" (and other similar phrases as well).


How do I get a lot of backlinks to point to my site?

A good place to start is to submit to directories. Start with the free ones and then decide whether pay ones are worth it for you. Here's a great place where you can find a free directory listing that sorts them by PR, Alexa rank (worthless), and more: http://www.tipsntutorials.com/Top-Directories/ and also check out http://www.isedb.com as it lists thousands of place you might find worth submitting to.


Why does <website goes here> have such a high PR/high ranking with so few backlinks?

1) They have a lot of low PR links pointing to the home page. These usually don't show in Google's backlink report but can still propel a site high in the rankings.

2) They have a lot of links pointing to internal pages within the website. These links will only show when you do a backlink report for that specific page, not the homepage. These pages usually pass on a lot of PR to the site's home page and propel it in the rankings.

3) Web pages with high PageRank have linked to the site's home page. High PR links carry much more weight then links from low PR pages. A link from a PR8 or PR9 page can make quite a difference in a web page's PR and ranking.


My site has gone from PR<whatever> to zero. (Or the Google Toolbar is greyed out) Why?


or

My site has disappeared from the SERPs. Why?

This seems to happen on occasion and the natural tendency is to think you've been banned. However, this is rarely the case (if you've been doing bad things then you're not asking this question because you already know why this has happened!). For reasons known only to the powers to be this just happens. After a while, usually next update, things return to normal. What can you do about it? Nothing really. You can write to Google but all you'll get is one of the generic responses that doesn't really tell you anything. The best thing you can do is to sit back, have a beer or three, and wait for things to be set right again....on their own.

Also, new websites can take a while to have visible PR assigned to them. This doesn't mean the site doesn't have PR. It just means the Google Toolbar or other methods of checking just haven't been updated yet.


I was thinking of doing <seo trick here> to my site but I'm afraid the search engines might think it is spam. Should I do it?

No. Why? If you're not sure if it will get you in trouble with the search engines or not then it's probably something you shouldn't be doing. Another good reason not to do it is accessibility. Many webmasters employ hacks and tricks in an effort to increase their search engine ranking. Often times these tricks are at the expense of the usability of their website. Not only to those who have disabilities but to anyone who's trying to navigate their site.


How many keywords should I put into my <title>, <a>, and <h1>..<h7> tags?


You should only put the few keywords that are most relevant to your pages. The more you put in each tag, the more you dilute the value each keyword is given.

<h1>Advanced PHP Programming</h1>

is better then

<h1>Advanced PHP Programming Is Really Cool And Stuff Dude</h1>


...blah...blah...Meta Tags...blah...blah...

The large majority of search engines do not use Meta Tags as part of their ranking algorithym. The most notable exception is Yahoo which does use them (at least the meta keyword) but it's weight in their algorithym is extremely low and essentially has no influence on a high ranking (it may be useful to jump up you from the 1,000th position or so). Some will claim Google uses Meta tags in its algorithym. This is entirely untrue. Google, however, will use a meta description tag if it is unable to discern a description for a webpage on its own (if the page has no text and no description in the open directory [dmoz] the it is likely Google will use the meta description tag in its SERPs). Please note that it is only using this description in its SERPs, not its algorithym.

Should you use Meta Tags in your site? Yes. They do have some affect in some search engines and even though that effect is almost zero it is still more then zero so is worth the time.

How much time should I spend on my Meta Tags? Ten minutes. Write a nice concise description of your page and throw in a sampling of keywords (which you should have them handy if you've optimized your pages properly). You should spend no more time then this on them. Use your time to promote your site and get quality inbound links.

How many keywords should I use? As many as you want. If you start to think you may have too many, you probably do. This means you need to divide your page into subpages with each one taking its own topic.


Should I submit my website to the Search Engines by hand or use software?

Do it by hand. It will not take long to do and will ensure that you are successful in submitting each form with the correct information. There is a constant debate about how search engines feel about automated submission software. Since there is a reasonable chance these are frowned upon by the search engines, and since you can do anything they can do on your own, you might as well avoid them.

But, if you're going to use software, these title seem to be the most common ones recommended:

Addweb: http://www.cyberspacehq.com/products/addweb/
Web Position Gold: http://www.webposition.com/
Web CEO: http://www.webceo.com/


Why doesn't Google index all of my site's pages? Why does Google update some pages more often then others?

1) Your site is new. You don't really expect Google to index every page you have immediately, do you?

2) Your site has low PR. Consensus indicates that Google will crawl sites that have higher PR deeper then sites with low PR. They figure the more popular your site is (PR is a popularity contest, remember?) the better a resource it must be.

3) Your site uses dymanic pages/session ID's and they are not search engine friendly. Session ID are search engines like garlic is to vampires. They repell them. Have your site remove them when the bots come around and you will fare much better (yes, this is ethical and acceptable to the search engines). Query strings that are either very long or conatin "id=" tend to limit the amount of pages some search engines will index (Google is a good example of this). Change "id=" to "page=" or something similar and you should do better. Or read the article about search engine friendly web pages.

If a site has high PR and updates its content frequently, Google will index its pages more frequently (usually every few days or even sooner) then low PR sites that do not update frequently.


How do I stop search engines from indexing some of pages?

You can use a robots.txt file to tell search engines (and other bots, too) where they can and cannot go. An excellent tutorial can be found at http://www.robotstxt.org/wc/robots.html. And an excellent example of one can be found at WebmasterWorld: http://www.webmasterworld.com/robots.txt.


How should I handle external links? (Because I don't want to send PR out of my website)

Outbound links are a balancing act. You need to decide how much PR is worth to you (as compared to your users' experience at your site) and then decide what is the best way to acheive your maximum PR without sacrificing a satisfactory user experience.

One thing you could do is use a robots.txt file to prevent search engines from crawling pages with outbound links. Then no PR is lost because the search engines aren't even crawling those pages. But keep in mind that any internal links on those pages won't be counted either. This is common to do with a directory.

Another thing you may want to try is to use a script that redirects users to external sites (example: http://www.domain.com/outboundlinks.php?id=linkidhere) and then put outboundlinks.php into your robot.txt file. Then the search engines won't follow the links because they can't access the script that does the redirect. Why would you want to do this? Becasue search engines do follow redirect scripts so the PR is being sent out of your site anyway.

The latest technique available is to put 'rel="nofollow"' in your anchor tag. Google, and others I do believe, will no follow these links and in Google's case not pass along PR.


Does having Adsense on my website help me with my search engine ranking?

Not really. It may get Google to spider your site more completely and frequently as it needs to know what the content is on your pages so it may serve up the right ads. But it won't give you a boost in any way in the rankings. Won't give you any extra PR either.


Pages with .php extensions don't rank as well as pages with .html extensions

This is a very common myth that is 100% untrue. The file extension does not affect your rankings in any way. After all, no matter what server side programming language you use, and what extension you choose to use with it, they all just spit out HTML in the end. That's all a web browser will and that all a search engine will see.


Sites with .com rank higher then with <TLD here>

This is another common myth that is untrue. The only time a domain extension can affect your ranking is if the search is based by country. The country-specific TLDs (e.g. .co.uk) will have priority over non-country specific TLDs (e.g. .com or .net).


Pages with query strings don't rank as well as without query strings

Another common myth that is untrue. The only way variables in a query string can affect a site in the SERPs is if it has a sessionID or something that looks like a sessionID in it (e.g. id=123456). These usually prevent indexing of these pages or limit the amount of pages indexed. But query strings do not affect the page's ranking. Neither in a positive way or negative way.


When is Google going to do its next PR update?

I don't know. He doesn't know. She doesn't know. Nobody knows. So please stop asking!

Google has been updating in an irregular manner for some time now so it is impossible to say when they will do an update again. It is a common belief that their updates will be done on a quarterly basis now. Since we have yet to see a consistant pattern this can only be considered speculation at this time. Your site has PR even though you can't see it. Even though Google's updating of their toolbar has become inconsistant their updating of PR has not. You just won't know what is it until their next update.


What would be a good SEO strategy?

Before you launch your site, you should have done the following:
- Optimized your <title> tags on each page to contain 1 - 3 keywords
- Used appropriate markup where necessary (<h1>, <em>, etc.)
- Used keywords liberally yet appropriately throughout each page
- Designed the navigational structure of the site to channel PR to main pages (especially the homepage)
- Used Search Engine Friendly URLs (if necessary)
- Created a complete website with plenty of quality content
- Used keywords in your domain and url (http://www.keyword1.com/keyword2/keyword3.html)

Immediately after launching your site you should do the following:
- Submit your site, by hand, to all major search engines
- Submit your site to all free directories (dmoz, yahoo (if applicable), etc..)
- Begin a link building campaign (attempting to get keywords in the reciprocal link anchor text)

Finally, as part of an ongoing strategy:
- Continually update your website will quality content
- Continually seek free and reciprocal links preferably from sites in your genre


Good SitePoint Forum Threads that you might find useful:

Search Engine Articles and Resources: http://www.sitepoint.com/forums/showthread.php?t=53874
Want to know more about Google?: http://www.sitepoint.com/forums/showthread.php?t=76257
What is duplicate content?: http://www.sitepoint.com/forums/showthread.php?t=167998
How to get 50,000 pages spidered by Google:
http://www.sitepoint.com/forums/showthread.php?t=169706
Effect of a domain name on SERPs
http://www.sitepoint.com/forums/showthread.php?t=176254

Good SitePoint Articles that you might find useful:

Search Engine Friendly URLs:
http://www.sitepoint.com/article/se...e-friendly-urls
Top Ten Google Myths Revealed
http://www.sitepoint.com/article/to...-myths-revealed
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