What you're seeing, in this exercise, are unvisited (called generally "links") and visited ("visited links") links. In this blog, unvisited links are blue, and visited links are purple.
The concept of colour changes for visited links has been with us since hypertext was invented. Websites like this one, that use visited links with colour changes, indicate to you when you view text containing links that you have already followed. Unvisited links vs visited links become relevant here, because this blog, like many Blogger blogs, hosts the permalink to the posts in the post titles.
If you click on a link to this post, any link to this post changes colour, in your browser - where that link is hosted on any website that supports visited links. If you clicked on a direct link to this post to get here, the title Links In The Title Cause Titles That Change Colour should be purple. If you are viewing this blog having followed a link to the main page "The Real Blogger Status", or using a Topics link such as "Links", you're possibly seeing a few post titles in blue.
With some blogs, you will see blog titles that change colour. Since this blog uses a custom graphic title, and a custom menu bar that contains a "Home" link, the title is not text, and does not change colour. Many blogs that use plain text titles and support visited links will exhibit the same colour change.
Note that I said, above
If you click on a link to this post, any link to this post changes colour, in your browserThis colour change is retained in the browser history settings. If you indiscriminately clear cache and cookies, you may also clear browsing history. If you clear browsing history, all links will change to unvisited colour. Note also that "visited links" have an expiry period, so you are encouraged to revisit links after the expiry period passes.
If you wish to change the colours of the links in your blog, and the blog has a standard layout or designer template, you use the Template Designer wizard. The Advanced - Links menu, in most templates, provides 3 options - "Link Color", "Visited Color", and "Hover Color".
The colour change will be a challenge when designing many blogs that use Designer templates, and use the complex colour palettes and patterned backgrounds. Using "links" vs "visited links" will necessitate careful choice of three colours - links, text, and visited links - that are simultaneously
- Are readable, against the background.
- Noticeable, but not glaringly so.
- Visibly different from each other.