One of Flickr's great advantages is that it is very easy to use, even if you are not a computer guru. Uploading and organizing your images is very simple and intuitive. You can store your images in "Sets" or "Collections" and you can even have "Collections" of "Sets". Your front page features your "Photostream" which displays your most recent uploads, and, depending on the layout you choose, your sets or collections as well.
Flickr makes it easy to share photos via email and via Twitter and Facebook. For many blogging platforms, you can also send your Flickr images direct to your blog if you wish. Or you can embed a slideshow into your blog posts or web pages, as I've done below.
Flickr also allows you a lot of control over who sees your images and what license you want to apply to them. There are a variety of ways of controlling who sees what, ranging from full public access to completely private. And, if you want to keep your images private, but would still like to share them with certain people, you can create Guest Passes that achieve just that.
Flickr doubles as a powerful and lively image orientated social network that allows you to participate as much or as little as you please. You can join or create Groups that focus on a great many different subjects as well as "Favorite" and comment on images and create Galleries featuring the work of other users.
Flickr offers a free account that should be more than adequate for a lot of users. And, if you want more storage and other extras you can upgrade to a Pro account for a nominal yearly fee.