|Image credit: Paul K on Flickr|
Basically, these snippets of code are appended for tracking purposes. They are generated by certain analytics services in order to help organizations get a better idea of how visitors arrive on their web sites and how their content is shared across the web.
Here's an example of code added onto the URL for the home page of the Journal of Immigrant and Refugee Studies, published by Taylor & Francis:
Here's another example of similar code, this time appended to the URL for Eldis' Conflict & Security page:
Both are generated by a service called AddThis, which also provides code for the "share" and "follow" buttons that a lot of web sites use. For more information, read about their social analytics offerings; see esp. the introduction to "click tracking" and "address bar sharing."
I copied a portion of text from Forced Migration Review's web site recently to use as a part of the blurb describing the theme of their latest issue on Afghanistan. When I pasted it into my blog post, a "see more" reference was appended, as follows:
FMR 46 contains 21 articles on Afghanistan, plus a mini-feature on Statelessness. - See more at: http://www.fmreview.org/afghanistan/contents#sthash.lAmfxDCc.dpuf
A similar "see more" reference is displayed when you copy and paste from Refugees International's web site. Both sites use the ShareThis widget, which offers a CopyNShare feature for tracking the sharing of content.
Google Analytics allows web sites to get more data about where their visitors are coming from by setting up "custom campaigns." Using what are referred to as UTM tags, you can create customized URLs for very specific tracking purposes. Here is an example from the Brookings Institution, which presumably indicates that the visitor (i.e., me!) came to their web site via an RSS feed:
In each of these cases, the extra code does not affect the validity of the root URL. In other words, you can remove it and the URL will still work. How do you know what to remove? Basically, anything from the hashtag on in the first two examples and from the question mark on in the third example. So here is what the root URLs would look like without the appended tracking codes: