I already have a Tumblr account, but I wanted to branch out a bit for my "hands-on play" part of this assignment. I decided to look more closely at some library-centric blogs and see who was commenting and reblogging from them.
The obvious choice was libraryjournal.tumblr.com, the Tumblr account for Library Journal. This Tumblr blog features about half original posts about Library Journal articles and about half reblogged posts from book blogs about publishers and library-related humor. As a more "official" looking blog, this Tumblr blog is great at tagging its posts and keeping things organized. The blog's theme is white and simple, and features links to Library Journals elsewhere on the web. It's a stark contrast from other Tumblrarians blogs, which are often colorful and cluttered with fandom posts and personal conversations.
Blogs that Library Journal reposted from included Patron Debris, Chicago Public Library, and National Public Ration. The demographic that reblogs original Library Journal posts is predictable: librarians and librarian-run library blogs like ferndalepubliclibrary and thoughtsofaschoollibrarian.
I also noticed librarians using other Tumblr blogs to self-promote themselves and their own blogs. For example, the blog Librarian Wardrobe encourages librarians to submit photos of themselves wearing their "library gear" and to briefly state their job, their library, and their city. Other blogs, like I Work At a Public Library, is mainly curated and written by one librarian, but occasionally other public library workers submit images and stories to the blogger so that she can edit them and add them to the blog.
One tumblrarian I follow, booksyarnink, linked her blog to Instagram and wrote a post promoting a review she wrote that was published in the print edition of Library Journal. As of yet, the post has only generated "likes," not "reblogs." Reblogging is the Tumblr equivalent of "sharing" a link on Facebook. A post is likely to get more press if it is reblogged because other Tumblr users that don't follow the original posting blog may follow any number of blogs that a post gets reblogged to.
I have yet to figure out why some users follow the blogs they do. Most of my followers are fellow librarians or library students interested in the same things as I am. Tumblr is like my own little filter bubble in which I only see things I like. This has nothing to do with an algorithm, however: I specifically seek out and follow library, book, knitting, and social justice blogs. Most of my followers are the same. Sometimes I get a couple outliers, though, like the inspiration/fitness blog that reblogs a lot of images of women in yoga pants.
Tagging is used in a variety of different ways on Tumblr. If you download an add-on called Tumblr Savior, you can filter out a variety of content on your newsfeed that you don't want to view. Popular tags of this type are "nsfw" but one of my friends is super conscientious about tagging anything that might be a "trigger" for someone with a mental illness--her tags include "body image tw" "food tw" "violence tw" and "scopophobia tw." I use tagging primarily as a search mechanism and try to guess the sorts of things that users would search for when looking for a post. For example, I've posted several gif sets related to the Wes Anderson movie, The Grand Budapest Hotel. My tags for those posts looked something like this: "wes anderson, movies, the grand budapest hotel, the grand budapest, grand budapest hotel." Tagging in this way has increased activity--or the amount of likes and reblogs--on my blog.
Tagging can also be used as a way to converse with readers without actually commenting on a post. One librarian tagged a gif set post with "woody allen" for people who may be searching for posts on Woody Allen, but then editorialized her post with the next tag: "who is still a doucher of epic proportions."
Finally, I took a look at the "Recommended Blogs" tab on the side of my newsfeed. I'd never really paid attention to it before, but I discovered that its recommendations were actually spot on. Tumblr somehow managed to find a blog which, on its first page, had posts not only about libraries, but about Jacques Tati and Elvis Costello, both of whom I am interested in but have never previously posted about on my blog. How did they know?! In this way Tumblr reminds me a little bit of Netflix and their film recommendations.