Vector graphics

There are mainly two type of image files. They are
                1. Vector graphics
                2. Bitmap or Raster images
              

1. Vector graphics
Vector graphics use mathematical relationships between points and the paths connecting them to describe an image. The path is a straight or a curved line. Vector graphics are composed of paths.
Vector-based graphics  are mathematically described and appear smooth at any size or resolution.


2. Bitmap or Raster images
A bitmap image uses  pixels where each pixel can be a different colour or shade. Bitmaps are composed of pixels.
Bitmap images require higher resolutions and anti-aliasing for a smooth appearance. 

Difference between Raster and Vector graphics

Raster graphics	Vector graphics
These are composed of pixels.	These are composed of paths.
Raster graphics can draw curves,polygons  only by pixel approximation.	Vector graphics draw continuous smooth lines.
The size of image is always fixed to some pixels. If we want to increase its size the image becomes blurred	The size is mathematically defined in terms of ratios,proportions,width,height. Every time you resize the image the lines are recalculated. So the result image remains sharp and clear.
File extensions : .BMP, .TIF, .JPG, .GIF	File Extensions : .PDF, .SVG, .EPS

Advantages :

Vector images usually require less disk space compared to bitmap.

Vector images don't lose quality when you scale them.

Dis advantages :

Not good for photographic images.

Vector images are not as cost effective as raster images.

The image which containing trapping information only scaled up to 20%.