Adobe Illustrator is a vector graphics editor developed and marketed by Adobe Systems.  Vector graphics is a technology that allows objects to be infinitely scalable to either very large or very tiny sizes without degradation in quality.  Often when an image is expanded to a large size the image distorts with rough squares and sharp edges, known as pixels.  This is a raster image which is based with a particular size in mind.  Vector images are based on geometry and relative location and angles, so its proportions can be scaled in any direction without pixelation or distortion.  Illustrator also includes 3-dimensional capabilities allowing users to extrude or revolve shapes to create simple 3D objects.

Adobe Illustrator CS6 is being replaced with Adobe Illustrator CC.