I have a div with some sentences that I don't want to be indexed by search engines.
Is it possible to somehow hide this from Google in a way?
I thought about using frames, and having the site within the frame being blocked by robots.txt, but I've never liked the idea of using frames.
Are there other options?
Technically, you could use iframe and put <meta name=robots content=noindex> into the iframed document. Using suitable attributes and CSS, you can make the iframed document appear as part of the page, mostly, though you would still need to reserve some fixed area for it.
Or you could generate the div with JavaScript, thought then it would not be seen when JavaScript is disabled. Note that search engine bots may execute JavaScript code and might thus “see” the generated content, though I would not expect that to happen now or in the near future.
If the content is text, without internal markup or images etc., you could have an empty div with a CSS rule that adds content using the :before pseudoelement and content property. This would fail for users with CSS disabled or with an aggressive user style sheet, and search engine bots might some day start interpretign CSS.
There might be trickier methods, too, but as a whole, there is no good way I think. It’s probably more useful to consider why you would want to prevent from finding the page on the basis of its content. As a tool for hiding information, it would be inefficient.