THE SECRET OF THE BUTCHER'S APRON
Every woman knows that horizontal stripes are a no-no if you want to flatter the figure.
With GIF bitmap images it's the other way round.
The file on the left is 1,210 bytes. The one on the right with the horizontal stripes is exactly the same size and has the same number of colours. The only difference is the direction of the bands of blue. Yet Horizontal Stripey weighs in at only 974 bytes.
Why? Because GIF bitmap images scan from side to side across the picture, noting whenever the pixel colour changes. There are many more changes when the stripes go from top to bottom. This makes a larger file.
Yes, yes, I know it's a small difference; but small differences make a big difference when you are optimising small bitmap images!
Anyway this is something you may like to bear in mind when you are making GIF bitmap images for phones, emoticons, logos or other graphics you need to keep at the smallest possible size.
Of course when we're talking of GIF optimization, nothing beats Photoshop Save For Web for dramatic file size reductions.
You may associate Photoshop with huge graphic files, but Photoshop is good at small as well.