There is perhaps no more abused or abusive HTML document device than the <blink> tag extension for text content currently supported by, thank heaven, only the Netscape browser.[1] It works by alternating the color of the text enclosed between the <blink> tag and its end tag (</blink>)--incessantly! It's not only ugly (reminiscent of the very bad video-text displays on a hotel TV), but it's excruciatingly annoying. The reader can't turn it off except to scroll beyond that portion of the document or hyperlink out of the document altogether. [<blink>, 4.5.3]
[1] Few Web surfers use Internet Explorer, so you rarely and thankfully won't find many HTML documents using the browser's equally tacky <marquee> feature.
Okay, so it grabs readers' attention to an important point. Just make sure it's a very important point. And here's a tip: Make it easy for the reader to get by the blinking segment in your document. Surround it with empty space or with pleasant, but vacuous content that we don't have to read.