A week ago we showed that Google is truncating URLs in some cases. To my surprise, Jaime from the Google Web Search team picked up the story and decided to explain why Google does shorten URLs. He decided to post the details in a Google Web Search Help thread and added a comment at the original blog post.
First, here is a picture of Google shortening a URL, so you know what I mean:
So how and why does Google do this in some cases? Jaime from Google explains:
When it comes to a page's URL, there are basically two competing goals we're trying to balance:
(1) providing enough info to help you make an informed decision on which result to click (2) presenting results in a easily readable and scannable format
Here's where the balancing act comes in: to accomplish goal #2, we'll sometimes omit parts of a URL (replacing them with ellipses) when we determine that those parts aren't critical to representing the page, and when doing so makes the search results page more readable. Not wanting to miss on goal #1, however, we won't leave out the page's host or domain, since we think it's important to know which website you're navigating to when you choose a result to click.
Of course, the rational is logical but it is nice to hear it from the 'horses mouth.'
Forum discussion at Google Web Search Help.