If you look to social media for opportunities to express yourself and see what others think about subject matter that interests you, signing up for Twitter gives you both a platform for your opinions and an opportunity to sample diverse viewpoints. Just as you make your tweets self expressive, you also can choose to customize your Twitter timeline and profile so they express your personality. Use Twitter's background image to highlight the sidebar area of Twitter's pages.

Sidebar Dimensions

To fill the sidebar of your Twitter timeline, you need an image that measures 400 pixels wide by 700 pixels high at 72 pixels per inch. If you choose to add a sidebar image, it replaces any background image you previously created. To upload your graphic, click on the gear icon on the menu bar of your timeline and choose "Settings." In the Design section of the Settings page, click on the "Change Background" button to access the File Upload dialog box. Set the "Background Position" radio buttons to "Left" so your image fills the sidebar area. Leave tiling turned off so your image remains restricted to the portion of the screen occupied by sidebar items.

Other Image Areas

Your timeline presents the most recent tweets from the people you follow as well as any posts you make yourself. Your profile page shows your own tweets, topped by two image areas, one superimposed over the other. The profile photo also serves in miniature as an avatar on your tweets. Twitter crops the photo you upload down to a one-inch square shape for your profile page. Behind it, the header image measures at least 520 pixels wide by 260 pixels high up to a target size of 1,252 pixels wide by 626 pixels high.

Image Specifications

Twitter sets separate file-size limits for each of the three images you can upload. The background image, which you use to create a sidebar, can range up to 2MB. The same limit applies to the size of your profile photo file. Headers must be no larger than 5MB. You can upload these files in your choice of PNG, JPG or GIF format. Unlike the background image, the header image uploads from the Profile section of the Settings page. If you opt for a GIF file, don't plan on creating an animation for any profile or timeline imagery, as Twitter's specs began banning animated GIFs in 2012.

Other Considerations

Twitter's rules outlaw certain forms of imagery, including pornography, for use in customizing a user profile, and require you to respect the intellectual property of others. If another user objects to your background, header or profile photo and files an official protest with Twitter, such actions can result in the deletion of your images if they violate the rules or another person's, company's or organization's copyrights or trademarks. Your own photographs or artwork make suitable uploads provided that they represent your own intellectual property.

Other Customizations

Along with imagery to put under your sidebar, you can customize the look of your timeline and profile page with additional choices in the Design section of the Settings page. Background Color determines the color assigned to screen area beyond a background image. Link Color controls the shade applied to links contained within tweets or displayed in sidebar information, including Trending Topics and suggestions of whom to follow. The Overlay setting -- black or white -- applies to solid areas of color that Twitter displays behind your tweets and the links in your sidebar. Set Overlay with a pair of radio buttons and click on the color swatches displayed for Background Color and Link Color to access built-in color pickers.