If you have had your logo professionally designed, you should have been given several different versions. Probably one for web use, one for print, maybe a reversed version to use on a dark background and a mono version. All of these could be in various sized jpegs, tiff, eps, pdf, giff or png file formats with possible Pantone colour references.
No wonder it can get very confusing.
Here is a guide to logo file types and when to use them. I have used a logo I designed recently for a new Nottingham baby sign language business, Ready Steady Sign as an example. I have also slightly simplified some of the information to make it easier for a non-graphic designer to understand. Please let me know if you think I have gone too far in the interests of clarity.
This is the format preferred by graphic designers. It is a vector-based file which means that it is scaleable and will look the same at whatever size you use it. It is editable in illustration and design programmes such as Adobe Illustrator but can be imported and opened by a wide variety of programmes including Word.
Most people are familiar with jpegs as this is the most widely used photo file type. A jpeg sees the logo as a photo, it has to be rectangular and puts white in the background.
This is fine if you are printing on a white piece of paper or web page but doesn't look so good on a coloured background like this web page. The other problem with jpegs is that they are limited in size, they are made up of pixels and if a jpeg is enlarged beyond the size it was created it will start to look jagged and blurry, see below.
What is more confusing is that an image that may look fantastic on your screen may not print perfectly. This is because your computer monitor works at a resolution of 72 dpi (dots per inch). Most professional printers need 300 dpi. So, before you send your sales flyer off to be printed you will need to be sure any jpegs (whether they are logos or photographs) are at least 300dpi at the size they are being printed. Your printer may have other specifications as well, so it is always best to check with them before sending artwork.
Jpegs can be saved at different sizes for convenience. A smaller file size may be perfectly adequate for printing on your own documents or attaching to your email signature and will not make emails and saved documents unwieldy. If you used a high resolution jpeg of your logo on every page of a document or in a powerpoint presentation it would increase the file size and slow down the speed at which your computer can handle the document. This means it is a good idea to have a small jpeg and a high resolution one available. I supplied one sized 89kb (for email use) and one at 438kb (to use at larger sizes).
3. RGB versus CMYK
Computer screens display colours by blending red, green and blue (RGB). Printers usually blend cyan, magenta, yellow and black (cmyk). If you send a file that is in rgb format to print, the colours might not turn out as you expect due to the way the software tries to interpret the colours. Photographs can be muddy or logo colours a different hue. Using a cmyk version of the logo will solve this. Below are the rgb and cmyk versions of the logo side by side. The red and orange look similar but the greens are different. Obviously you are viewing both these on an rgb monitor, if the cmyk logo was litho printed it would look much closer to the green of the other logo than if the rgb logo was used.
A png (Portable Network Graphic) file is specifically designed to display well on the internet. It is usually a particularly small file size so lets web pages load quickly and has a transparent background. It is not compatible with many professional printing software programmes.
Sometimes you may want to put your logo onto a dark or black background. Colours can clash or the logo may not be easy to read or recognise. If there is any black in your logo, stick it on a black background and it will disappear. You therefore need a reversed version.
Less used nowadays as email allows us to use colour cheaply, a black and white version of your logo used to be important. For example for fax header sheets or on documents that are being photocopied, a true black and white (or in this case greyscale) version of your logo will look crisper and be more consistent than using the colour version.