Adobe Illustrator, InDesign, and FreeHand are object layout applications. They handle two different kinds of object: Vector and Raster.
Vectors are defined mathematically. Vectors are resolution independent, so they can be scaled to any size with absolutely no loss of quality.
Raster images are fixed resolution bitmaps with a set pixel dimensions. Scaling a 2“ by 2” raster image to 4” by 4” reduces the number of pixels per inch by 50%.
Pay careful attention NOT TO SCALE A RASTER OBJECT so that the print output is less than 300 PPI. For a raster image to print properly, it must be provided at 300 pixels per inch (ppi or dpi) at the final output dimension.