Picasa is Google's photo sharing site. As you might have guessed by now, it's linked to Blogger. Whenever you upload an image to use in a Blogger post, it goes into its own album in your Picasa account. You can also pull images directly from your Picasa albums to place in your blog posts. Since Picasa has its own built-in image editor, this offers an easy way to tweak and organize your images, all with easy access from your Blogger admin panel. You can even tag and share the photos in your posts with your Google+ social circles.