Tumblr is a micro-blogging platform and social networking website, that allows users to post multimedia and other content to a short-form blog, named "tumblelog". Users can follow other users' blogs, as well as make their blogs private. Much of the website's features are accessed from the "dashboard" interface, where the option to post content and posts of followed blogs appear.
Resources required: 
PC/laptop, internet connection (not necessarily broadband), email address
Completely free
Setup and configuration: 
Go to Tumblr.com, enter your email address in the username field and choose a password for your account.
On your tumblr you can post text, photos, quote, link, chat, audio and video using the dashboard. The choice of font style, theme, is the user’s responsibility. At the top right you can display people who have joined your group and you can also invite new
Navigation and operation: 
The dashboard allows you to navigate and to manage your blog.
How to use it: 
Once registered you will have access to the Dashboard, where you can manage your blog (which may in fact be more than a single user), set preferences, build your network of connections with people, and decide the look and feel of the blog. To customise select the Customize button in the right sidebar of your admin panel, you will have access to the section that lets you choose the name, a brief description of your blog and graphics that you like. There are a number free templates that can be personalized, and some for sale. Once you choose a theme you can customize the basic level, add static pages, and connect, wherever possible, to your Social Networks. Publish your content On Tumblr you can add lyrics, post photos, post quotes, share links, publish audio and video files. Build a network of connections According to category of interest (topics) you will find archived materials from the most influential bloggers. You can follow them and their posts will be published in your timeline. You can also be followed by others. Reblog content of others Tumblr is also described as a Content Curation application. The platform will allow you to add contents from other Tumblr users.
Examples of use: 
Art history lesson: The teacher posts a lesson document about an artist/painter, representing an introduction to the artist’s style. Students have to study it and add as comments paintings and other comments that are synergetic to the artist.
Other issues: 
Some issues with micro-blogging are privacy, security, and integration. These are general issues with all uses of Web2.0 tools and can be overcome.
Useful tips: 
You can have a direct link with you facebook or twitter contacts. Other useful link related to Tumblr are: Blogger Wordpress