These are images from some of the observations by NASA's Hubble Space Telescope. They are made available by the Educational and Public Affairs Office of the Space Telescope Science Institute. These are digital versions of pictures distributed publicly as press releases. Click on the image to see a full size version in JPEG format.
Different formats are available because they provide various capabilities.
Note that these are presentation pictures, not raw data appropriate for scientific analysis. They have been processed extensively, usually consist of composited multiple images and may have annotations superimposed.