What kinds of file types there are and which ones should we use when creating icons?

An icon is a representation of an object which we can select in order to perform a particular operation. Through years, icons have evolved, showing more outstanding graphics and at the same time, allowing multiple file types depending on the use we have for them. Icons are one of the most important parts of a project, no matter if it's a web page, software, or any application. They are the first thing the user sees, that's why in order to catch their attention, they have to be showy (in the good sense of the word). Different formats give us more chances to work with the quality of the image, that's why, based on an icon designer's opinion on the subject, we are going to check them out.

Currently, there are many types of image files. Each one of them is used for a certain type of applications. When we want to work with icons, the most popular formats are ico, png, bmp, gif and tif. First, we're going to explain what does each one of this extensions means and when should we use them.

.ico: The ICO file format, is the format used by icons in Windows. It contains two bitmaps, one which contains the image mask to define transparency (called AND) and another one which contains the icon mapped into the image mask (XOR).

.png: This file format is quite popular thanks to it's loss less compression. This type of images must be static, but allows 8-bit transparency channels (this means we can fade colors). Right now, this format is supported by almost every browser which makes it one of the best options in the market.

.bmp: BMP format is perhaps one of the oldest and popular formats there are. It shows an Uncompressed raster image, composed by a grid of pixels forming an image.

.gif: It stands for Graphical Interchange Format File and can contain up to 256 indexed colors. It's a loss less format that supports animated graphics, but, unlike png files, fade transparencies are not supported.

.tif: TIF files are used by high quality graphics with many colors. It supports layers and pages. You can choose whether you want to save the file in an uncompressed format, or with a JPEG compression type.

Since each one of this file types have pros and cons, this graphic will help us decide which one we should choose.

According to de chart, we should always use png, gif or tif files in order to get the best quality and the smallest file size. With this file formats, we can then create our .ico files and still get the same high quality results.