Blog is a portmanteau created from the words“web log.” A blog is effectively the equivalent of an online journal or diary. You can write whatever you want: commentary, recaps of events, thoughts and opinions, summaries of research or development in your field. Most blogs have an option for others to follow your posts and make comments.
Geosocial or location networking is generally via phone or tablet apps as opposed to web-based software, as they rely on geotagging your location. Apps use your location data to connect you to people with similar interests in your local area or to broadcast your location and activity to friends and wider audiences.
A good example of a geosocial app is FourSquare, which you can use to 'check in' to locations and earn 'badges' the more frequently you visit a particular location. Many businesses use these kind of apps to make special offers and discounts available to regular customers.
Aggregators are services that allow you to collect content from several different social media sites in one location. They are used to simplify the process of using social media, something that can prove very useful if you have multiple accounts across, for example, Facebook, Twitter, LinkedIn, Digg, Delicious etc.
Programs like TweetDeck allow you to add all of these separate accounts within a single location, so instead of having to check each site for updates, they are all combined. You can also use these kinds of aggregation services to follow particular hashtags, users or RSS feeds as well.
Microblogging is similar to blogging in the sense that you can write whatever you choose, share your thoughts and opinions or link to interesting websites or online articles. However, on Twitter, for example, you are limited to 140 characters, so it is much more akin to sending a text message than writing a journal entry.
Social networking sites are generally purely built around the concept of communication. Many are multi-functional, in that they will include options such as geotagging, microblogging, document sharing etc.
Facebook is a good example of this. Status updates are the equivalent of microblogging, in that the amount you can write is often limited. You can also share images, videos or links; 'check in' your location at particular places; use plug-ins for services such as GoodReads or Last.FM to share what you are reading or listening to.