A logo is a graphic mark or emblem commonly used by commercial enterprises, organizations and even individuals to aid and promote instant public recognition. Logos are either purely graphic (symbols/icons) or are composed of the name of the organization (a logotype or wordmark).

Today there are many corporations, products, brands, services, agencies and other entities using an ideogram (sign, icon) or an emblem (symbol) or a combination of sign and emblem as a logo. Currently, the usage of both images (ideograms) and the company name (logotype) to emphasize the name instead of the supporting graphic portion and making it unique, by it non-formulaic construction via the desiginal use of its letters, colors and any additional graphic elements.

Logo design is an important area of graphic design, and one of the most difficult to perfect. The logo (ideogram), is the image embodying an organization. Because logos are meant to represent companies' brands or corporate identities and foster their immediate customer recognition, it is counterproductive to frequently redesign logos.

Color is considered important to brand recognition, but it should not be an integral component to the logo design, which could conflict with its functionality. In the United States red, white, and blue are often used in logos for companies that want to project patriotic feelings. Green is often associated with the health and hygiene sector, and light blue or silver is often used to reflect diet foods. For other brands, more subdued tones and lower saturation can communicate reliability, quality, relaxation, or other traits.

Starting about 4 years ago, certain companies, especially online technology companies, began to adopt a common look and feel. Many people refer to that standard as "web 2.0", but there is no official "web 2.0" standard. Web 2.0 logos often use small chunks of large type, with bright and cheery colors. Although there are literally hundreds of fonts used by web 2.0 companies, the logos are generally dominated by soft, rounded san serif fonts such as VAG Rounded (Crowdspring) and Helvetica Rounded (Skype). There are, however, numerous exceptions, as some web 2.0 companies have used classic fonts (Trade, News Gothic, Frutiger, Helvetica), while others have chosen to differentiate completely, using fonts like Klavika (Facebook).