Who hasn’t been confused by image file types at some point? What’s the difference? Why choose one over another? In all honesty, it’s as pretty hefty subject. But here is some very basic information on the most common image types (in a very small nutshell).
First, the extension of a file can serve to tell you what type of file it is. An extension is what comes after the dot. For example, a photo might be named image02.jpg. The extension is “jpg.” That means it is a JPG (pronounced “jay-peg”) file.
JPG (or JPEG)
This is a very common file type that you’ve probably seen many times. The size of these files (how much information it contains) is generally smaller than other file types because of how the information is compressed, or made simpler. Quality can vary, depending on many different factors, so users must beware (as always) if the image is going to be used on a printed piece, as printed material generally requires high quality, which creates a crisper/cleaner image. A drawback to using JPGs in graphic design is that the background will always be a solid color. For example, if you have a logo that is saved as a JPG file and you want to place it on a colored background, there may be a white box behind it. JPGs can be used in print and on websites and social media.
This type of file supports a kind of compression that preserves the data/information. The end result is a higher quality image than some other file types. The greatest advantage to using a PNG image is that you can use a transparent background. In the example of the logo, this way the graphic could be placed on any kind of background without a solid box appearing behind it. PNG files can be used in print and on websites and social media.
This is also a very common file type, and is often used for archiving and sharing. They generally cannot be edited unless certain software is used. Depending on the program you use, you may be able to specify certain privileges, making it a good file type when security is an issue. Oftentimes downloads from the Internet are PDFs, especially if it involves a large amount of text (eg: user manuals, forms, brochures, etc.) PDFs can be used for printing as well.
Similar to a PNG, a GIF’s compression preserves the data/information. Nowadays, you will probably see this file type used with motion – although GIFs can be static images just like JPGs or PNGs etc. A GIF uses multiple images that are looped, so it almost appears to be a short video playing over and over. If you’re a Facebook user, you have probably seen many of these as posts or comments. This is generally the common reason for saving a file as a GIF, but again, just because it is a GIF doesn’t mean it has to contain motion. They can also be printed or shared on social media. (It is an ongoing debate whether to pronounce it “gif” or “jif.”)
Of course, there are other image file types besides these, along with files that have nothing to do with images/graphics. Every time you use a computer, you may see .docx, .psd, .eps, .txt, or .csv, just to name a few, and each one reveals what type of file it is and how it can best be opened, used or shared. Next time you have trouble figuring how to best use a file, do yourself a favor and hop on Google, then ask what the extension means. Not only will you learn something new, but when someone else in your office doesn’t know what .indd means, you can be the guru.