Recently I had to explain to a friend with a little bit of experience with Photoshop and Paint Shop Pro why those programs weren't the best choice for a type of diagram he wanted to draw. Pixels he understood well enough. Vectors were a whole other language. Sometimes one quick explanation isn't enough to drill home the difference. After reading these tutorials, looking at pictures, and watching some videos you should have a much clearer understanding of how to create and when to use pixel or bitmap images and how to create and use vector drawings.
^{Graphic by J. Bear}

• Definitions: It can help to read different definitions of the same words because the way one definition is worded might click with you when another (describing essentially the same concept) doesn't.
  
  
  • Bitmap and Raster | Bitmap and Raster | Pixel | The Pixel
    
    
  • Vector | Vector | Metafile | Bezier Curve
  
  
  
• Video and Animation: Sometimes moving pictures are a better way to explain some concepts.
  
  
  • Vector vs. Bitmap formats is a one of the free demo videos from the VTC Professional Desktop Publishing on the PC series.
    
    
  • Pixels vs. Vectors from the Scanning Principles with: Taz Tally, Ph.D. is part of the free video content at Lynda.com.
    
    
  • Three InDesign Pen Tool Animations show how to draw straight lines, curves, and shapes with a vector tool.
  
  
  
• Articles and Tutorials: Now that you understand more about bitmap and vector, learn when to use each type.
  
  
  Best Graphics File Formats for Desktop Publishing describes the most common bitmap and vector file formats and when to use each one.
  
  
  • The Language of Curves provides a more in-depth look at vector drawing.
    
    
  • Pixel Image Editors and Vector Illustration Software explains what to look for in software for working with bitmap and vector images.
    
    
  • Use the Right Clip Art Format presents the facts about each graphic format in list form.