Adding a custom Twitter background makes your Twitter page and tweets stand out, and gives you or your organization a professional look. You can make one yourself (which you can do in Photoshop, or sometimes even with a simpler program like MS Paint). Note, this seems to apply only to larger browser screen versions, as backgrounds are not supported as of this writing on mobile.twitter.com browser or app screens.
Of course, you can “tile” a small image, which I think works well only if it makes a nice subtle pattern, otherwise it can be obnoxious.
Custom Twitter background dimensions
Ideally, you should use a single image covering the entire background space. Of course, you’ll need the custom Twitter background dimensions, including margins you’ll need for the main Twitter content. There has been a number of changes over the last couple years, down from 1280 to 850, now it’s back up again. So here is what I found through direct experimentation (September, 2012).
Generally you’ll want about a 194 pixel or less margin on the left side for the graphics that will be visible for most screen resolutions. You can use this space to provide contact information, or images of your products, or people using your product, but since it’s only an image, none of it will be clickable.
Here’s what’s been reported as the Twitter background left hand margin (screen resolutions as of 2011):
I’ve previously read that the Twitter background needs to be less than 850 pixels wide. However, I found this was not the case. I used a dimension of 1380 px wide by 800 pixels height and this worked well for me as Twitter did not resize the image (screen shot below). So, with this extra width, you can have graphic elements on both left and right margins of your main Twitter content. It is a big file but again, mobile web and apps currently don’t support the background…but stay tuned.