Mobile copy should be cut even more. Even if some of the following criteria lead you to include bylines, it might be better to remove them for the mobile version of your site.
For Bylines: Establish Credibility
Bylines can be worth their word count in the following cases:
If the author is famous — maybe even famous enough that people might read the piece mainly to hear what he or she has to say on some current issue. In this case, you should include the author's name when linking to the article from home pages, SERPs (search engine results pages), article listings, Tweets, etc.
Note that "fame" doesn't necessarily equate to "celebrity." Respected geeks can be well known in specialized communities, while being completely unknown to 99% of the population. What counts is whether the author is known to the target audience.
If the author has credentials or status that support the article's credibility. The classic example is a medical doctor writing about a health issue, in which case you should certainly list the article as being "by Joe Schmoe, MD."
If the author has experience that provides some credibility. For example, the designer of a website should be named when writing an article discussing that design.
If somebody often writes about a certain topic, regular readers might recognize the name and want to seek out the writer's other articles.
Opinion pieces, reviews, political commentary, and other types of content that are specifically positioned as an individual person's take on an issue need a byline simply to clarify the content's status. Depending on the nature of the site, such content might also require a disclaimer that the analysis does not necessarily represent the organization's position.
Finally, on intranets, naming authors can help establish a feeling of community by helping employees get to know each other (for more on this, see our separate report on intranet social media).
Usually, a brief author biography is secondary content that should appear at the bottom of articles. However, if a credentialed or experienced author's credibility-boosting effect requires more info than just his or her name, you should add a one-line bio abstract at the top of the page to encourage users to read the article.
Longer biographies should be relegated to secondary pages and linked from the author's name. But don't link the name to an email address, for two reasons:
It's distracting for users when clicking a name initiates an email instead of showing a new webpage, which is the expected behavior of web links. (This was #4 on my list of top-10 design mistakes of 1999, but I still see this erroneous design 13 years later.)
Users are much more likely to want read about the author than to contact the author. If appropriate, you can add contact info at the bottom of the biography page.
As my article on blog usability describes, author biographies should include a portrait photo, at least when you provide a separate bio page. This can be a standard headshot or an action shot of the author doing something relevant to the article (such as sitting on a tractor, for a farmer writing about farming).
Finally, the author bio page should include links to the author's other articles on the site, except in the case of weblogs or other sites that are essentially the work of a single author.