I'm learning search engine optimization.

Have gained some knowledge of the importance of the title and the description meta tag. I understand that text provided within the "description" tag can be used as part of the description in your eventual listing with a given search engine. Beyond that, I gather that content appearing near or at the top of your page gets used. This is where I have a question for anyone knowledgeable enough to lend insight:

At what point in the body of a page does a search engine typically start borrowing your content for use in its own descriptive listing of your site? What if it encounters a navigation bar first? A navigation bar doesn't usually qualify as readable text. Does it in that case intelligently move on to try to identify a heading or other piece of text to extract?

Kind thanks for any informed reponse.

tabloid

the way to tell the bot what to read first is to use the H1, H2, H3, etc. tags
The H1 tag being the most important content on your page. Since the use of those tags will increase the size of your text (this is what the tag was originally used for) you want to combine the use of those tags with some CSS on the text you are targetting. Both together you can still keep your content in check sizewise and also direct the crawlers to the most important parts of your content first.

Good luck!

That was a great reply. I make ample use of CSS and had therefore abandoned the use of H1, H2, etc. altogether.

Many thanks.

you're welcome. Just remember only one H1 tag per page, one H2 tag per page, etc. If not the crawler might think you are spamming your page to optimize your SE rank. They could ban you for it.