Showing whether a link on a web page has been visited or not can be very useful. One example that many will be familiar with is how it helps you know which links you have already followed from a Google search results page – links to pages you have already visited are a different colour than the other links.
Changing only the colour can be a bit subtle though, especially for people with colour vision deficiency. Depending on which colours are used to differentiate between visited and unvisited links it can be hard to tell them apart. To make the difference more obvious, there are a number of techniques involving background images, generated content (like the one I describe in Check marking visited links), and other CSS properties. However, if you’ve been using any similar tricks to style visited links, it’s time to forget about those and start relying on colour alone.
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