When you write your web page text so that it not only sounds natural, but also caters to the whims and fancies of the search engines so that they rank that page higher, it becomes SEO text.
Logically, there is not much difference between normal web page text and SEO web page text. Every well-written web page text is SEO web page text. As the search engines focus more and more on the contextual relevance of the text, it makes sense to write web page copy that is highly focused and targeted.
So why this differentiation between normal and SEO web page text?
The difference is between theory and practice. In theory you don’t need to use your keywords and key phrases strategically, but in practice, you have to, and this is the big difference. No matter what people say, I’ve personally observed that you can get a higher ranking by writing your text in a certain manner, and when you write your text so that it not only sounds natural, but also caters to the whims and fancies of the search engines so that they rank that page higher, it becomes SEO text. I’m not saying you have to be manipulative or you should create spammy text (needlessly stuffing your web page with your keywords) just to rank high — you may rank high by doing this for a few weeks, but then you may get blacklisted too. This is because the search engines want to provide quality text to their users, and what’s the use of visiting a web page that is full of keyword gobbledygook?
But you do need to use the keywords and you do need to use them enough times without sounding silly. SEO web page text achieves that for you. You write your text in such a manner that your keyword and its parts are scattered all over the web page and your human readers find it compelling, and appealing to read. You use your keywords at strategic locations, within strategic tags. They don’t have to be at the same place. Take for instance this page that talks about normal web page text and SEO web page text. These phrases appear all over this page in various combinations and sometimes “SEO”, “web”, “page” and “text” appear on their own without the other parts of the phrases.
The art behind SEO web page text writing is to strike a balance between your keywords and the rest of the text. Don’t use your keywords where they are not needed, but as and when they are needed, use them in a manner that the search engine robots and bots can easily locate them.