Guest blog is a practice of allowing another author to publish on your blog or website or publishing on someone else's website. This occurs when bloggers who post on a regular schedule have people write during vacations, to attract exposure, as a marketing tool, and as a leadership tool to develop newer bloggers.
Alan Levine keeps a cockroaches page on his website to track people who send unsolicited requests for guest blogging.
Richard Byrne an Educational blogger at tech4teachers uses guest posts to "opportunity to share their ideas and experiences." He creates a tag for all guest bloggers
Ethical ELA uses guest bloggers to post writing challenges for teachers
Guest blogging gets used in marketing campaigns to increase links and as an SEO hack.
Niel Patel, in the Ultimate Guide for Guest Blogging" suggests guest blogging gets, "more brand awareness and traffic back to their own website"
Popular bloggers will get unsolicited emails asking for permission to publish guest posts on their websites.
Some bloggers create a "Wall of Shame" to call out the spammy activity