What are vector and raster images? When should I use them?

Vector images are made up of thousands of dots, lines, and curves known as paths (each with a mathematical formula) to create a picture. Due to this formulaic approach, any of the lines and curves in the image can be assigned a different color. Vector images can be scaled infinitely and repeatedly as it does not lose its resolution. 

We would suggest you use a vector image while creating a logo, a letterhead or illustrations as you can increase the size of the image as much as you want, retaining its quality. The vector images can be used on from business card to billboards. Also, make sure that you use vector images while creating a type or a font as you can change its size without sacrificing on the quality.

The file formats for vector images are: .drw (vector file), .pif (vector image GDF format), .pct (Macintosh bitmap graphics format) , .ps (Adobe PostScript), .eps (Encapsulated PostScript), .svf (Simple Vector Format).

Tools:

• Adobe Illustrator: .ai, .ait, .art, 
• Corel Draw: .cdr, .cdrw, .cdt
• Corel: pat (Paint Shop Pro Pattern Image)
• Digital Line Graph: .dlg, .do
• OpenOffice: .odg

On the other hand, a raster images is made of pixels, each of different color arranged in a way that displays an image. But when you increase the size of a raster image, the images loses its clarity and becomes blurred or pixelates. Raster images are used with photos. You can use raster images while designing your websites, icons, banners, etc. 

Note: Avoid using raster images for creating logos as they will lose their quality when you increase its size.

The file formats for raster images are: .jpg (JPEG raster format), .gif (GIF transparent file), .png (Portanble Network Graphic Transparent file), .tiff or .tif (Tag Interleave Format).

Tool: 

• Adobe Photoshop: .psd