FORMATS
bitmap, gif and jpeg. photo formats are often used.

I make use of jpeg format for converting most big pictures, and reduce the dots per inch (dpi) to 70 or below, for a web page.

To keep jpeg document sizes under 50k, I use 30 to 60 on the compression scale for jpegs ( a scale runs from 2 as high quality, to 255 for low quality. )

Because many users employ a 256 colour palette, gifs are still much in use, but they only handle up to 256 colours. I make use of gifs for icons and small pics.

I make use of 24 bit colour bmps for archiving (I utilize 300 dpi in case I might print them later), they might be used as a source for both gif and jpeg.