Hi, I have a website in which I have black rectangular box in footer (in html, not an image). Can I place my optimized content (2-3 lines) in it and colour it black so that it will not be visible to users but robots can read it, my client wants it. No other optimized content in the website. Is this the ethical practice to increase the keyword density??? What are the consequences of it in future times if I use this??? Advice ASAP.....
This is a well known technique and the Google bots are not stupid, (as is using css, display:none, putting an image in front and so on). Although I don't know for certain if you will be punished for using such gray-hat techniques I know that, at the very least, all the keywords/links will be ignored by almost all search engines. FFMG
Tell your client that google quite specifically advise against it http://www.google.com/support/webmasters/bin/answer.py?answer=66353 Text (such as excessive keywords) can be hidden in several ways, including: * Using white text on a white background.... If your site is perceived to contain hidden text and links that are deceptive in intent, your site may be removed from the Google index, and will not appear in search results pages.
someday your competitors will find that and they will report you to google and you have a good chance to get your site banned
that will be considered as spam so i strictly suggest do not add conetent in colour black but u can add the content at the bottom which is visble.