I will not immerse you much in the theory of these formats. I will briefly tell you why I use different formats when fulfilling commercial orders.
PSD is the main file format for Photoshop, all layers of the image are saved in this format. After saving the PSD file, you can open it, for example, on another computer and continue editing layers, text and some filters that were previously applied. I also keep all PSD art files, even those that the clients approved. Sometimes it happens that the customer wants to make changes to the order in 1-2 months for an additional fee. Also, the PSD file conditionally confirms your copyright to art, and in case of theft of your art from social networks, you will be able to unquestioningly confirm your authorship.
When a client wants to make his corrections, he asks for a PSD file, and working with some companies involves transferring the PSD file for further editing.
Important Note: The PSD file does not save the previous steps from the last session in Photoshop. After opening the PSD file, you and your client will not be able to undo the actions by pressing Ctrl + Z, so try to leave as many layers in your art as possible just hiding them. Ctrl + Z can be applied only at new stages of editing in the current session. A PSD file with art can have an average weight of 50 megabytes to 900 megabytes, depending on the resolution of the file and the number of layers in the file. We use sRGB as the main color space.
JPEG (JPG) is the main format for saving web art for social networks and web sites. This format has a large compression ratio, which is why the image quality may be worse compared to a PNG file, which is especially visible with dark gradients. The advantage of this format is the weight of the file, which makes it easier to upload images to social networks with minimal file compression by the social network itself. I will tell you in Paragraph 12
how to properly save art for social networks. This file type has an average weight of 300 KB to 2 megabytes. We use sRGB color space.
JPG - the difference between JPG and JPEG is only in the letter «e». In practice, there are no differences when working with files of these formats. These are exactly the same image formats.
But why did two file extensions arise from the same format? It's very simple. In older operating systems, it was impossible to give a file extension a value containing more than three characters. In this regard, the JPEG extension was reduced to JPG.
PNG is the main file format if you want to keep transparency in the file (alpha channel) and publish the image on some web site. The PSD file also retains transparency (alpha channel), but the PSD file is technical with a huge weight and, unlike PNG, is not shown on websites. The PNG file has an average compression ratio and has an average weight of 1-5 megabytes. The PNG file conveys dark gradients very well, without the staircase effect (transitions between colors are less noticeable in contrast to a JPEG file in 16 bits). We rarely use this format to save art.
TIFF is the main format if we want to print art for the client. We also always give the client a TIFF file and indicate in the letter that this file is intended for printing. This format is used in printing all over the world, and provides the best color reproduction in print. The color space in Photoshop must be switched to CMYK. CMYK looks very dim compared to sRGB, so we do additional color correction of the art for the
CMYK color palette so that it looks as vivid as possible when printing.
After making the art, I advise from my experience to duplicate the JPG file with the sRGB color space, and switch the duplicated JPG file to the CMYK color space, and edit it for printing.
If we try to print a JPEG file (RGB), then most likely the person's skin color will be very pale, the colors of the art will be very dim, and the client will be very upset if he spends money on expensive printing in vain. So remember that we use only TIFF format for printing.
GIF – we do not use this format when saving art. This format is suitable for animated images. This format is similar to PNG, but it conveys color gradients very poorly and is not optimized in size.