A computer wallpaper is an image that is used as the background of a graphical user interface of a computer, mobile phone, tablet, or other electronic device. Depending on the operating system you choose, the terms vary, but they usually refer to an image that is chosen to decorate your computer desktop, lock screen, or home screen. In Microsoft Windows there is a wallpaper (or wallpaper in English), while in Mac OS there is a desktop image.
Images used as desktop backgrounds are usually bitmap images that are the same size as the screen resolution (such as 1024 × 768 pixels or 1280 × 1024 pixels). They are adjusted so that they do not exceed the dimensions of the screen. If they were too big or too small, they wouldn’t look very good. Many screen definitions are proportional (meaning that the length ratio equals the width ratio), allowing you to use the same image for these different dimensions while maintaining the correct shape (no gradients or gaps). If the image is stretched, there may be a loss of quality, and resizing may cause the computer to slow down slightly. Common image formats used in JPG and PNG desktop images.
For widescreen displays (such as 16/9 or 16/10 screens), the aspect ratio is not the same as for 4/3 screens. Therefore, 4/3 of the image needs to be cropped or stretched to fill the screen properly.