In CSS style table of website pages I have used a lot of hidden attributes
like overflow:hidden and display:none;
Does this has effect for SEO? Is this friendly for search engines (SE)? Can it be punished by search engine (SE)? Can hidden attributes in CSS style table of pages lower the website power?
Text within elements styled with display:none is not indexed by Google. So yes, this may affect SEO, depending on the actual content.
Hidden text is NOT OK if it's purpose is to affect the search index ranking, according to Google.
Read this for more info from Google:
http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=66353
@aicuxiao We're presuming that you're asking about whether hidden content affects what search engines will index, and therefore affect your natural rankings on non-paid search results.
It's important to think like a human when it comes to SEO—if you write content that you don't wish any person to see, presume that search engines won't see it either. It may be the case that some search engines will index hidden content and some will not. However, it is generally the goal of a search engine to serve relevant results to humans, and so indexing is likely to be tuned to "think" like a human when indexing. If you think with this mindset, you won't get caught out in the future by having some of your content removed from search results.
I hope that helps.
display:none has meaning for both visual browsers and voice browsers. In that it should be be ignored by both. visibility:hidden should only affect visual browsers. Please note that it is down the actual browser developers to obey these rules.
Most SEO companies would tell you to avoid using both too much, and some get scared of you using them to create CSS drop down menus!!
overflow:hidden will only block out text if height is also added to the element so I'd say that if you try and hide vast amounts of text within one of those search engines would figure that out to.
Basically if you think your being sneaky and clever but adding links and text that won't actually be seen by a regular user then the search engines will eventually if they don't already figure out what your trying to do and ban your page. If however you don't try and fool people and simply try your hardest to make the Web a useful and valuable place to find what people are looking for you'll do well.