The 5 Main Logo Styles
#1 - Symbol
This type of logo represents the company in a simple but bold manner. In most cases, the image is abstract and stylized to give visual interest. Most companies that use this type of logo will have a very simple main logo, but may choose to create additional alternative versions that appear a little more flashy. The human mind can easily remember a simple form much easier than a complex one. It’s best to use a simple symbol or icon if you plan on building a large business. You probably recognize symbol logos like Apple, Shell and Mercedes-Benz.
#2 - Word Mark
These are uniquely styled text logos that spell out the company or brand name. Many times, custom fonts are created specifically for brands to use across all their marketing and branding collateral. Some examples include Facebook, Disney and Sony.
#3 - Letter Mark
Lettermarks are exclusively typographic. They use a symbol representing the company through the use of its initials or the brands first letter. Many companies choose to use this type of logo because their initials can better graphically illustrate the company better than the full name (name is too long), the name is hard to pronounce, or it’s just not distinct enough to carry its own weight. Some companies and organizations that use lettermarks include Hewlett-Packard, Chanel and General Electric.
#4 - Combination Mark
These logos combine a wordmark and a symbol or icon to give the flexibility for the use of either or both elements across a variety of applications. A well-designed combination mark looks just as good with the elements separate as it does with them together. You might recognize some combo marks like Hawaiian Airlines, Adidas and Sprint.
#5 - Emblem
An emblem logo encases the company name within the design. Some examples include Starbucks, the NFL and Harley-Davidson Motorcycles.
Things to Consider:
Purpose
Corporate logos are intended to be the "face" of a company: They are graphical displays of a company's unique identity, and through colors and fonts and images they provide essential information about a company that allows customers to identify with the company's core brand. Logos are also a shorthand way of referring to the company in advertising and marketing materials; they also provide an anchor point for the various fonts, colors and design choices in all other business marketing materials.
Design Principles
Good logos should be unique and comprehensible to potential customers. Although there are myriad choices for color, visual elements and typography, in general a logo should help convey some information about the company, or be designed in a way that gives some sense of meaning about the company or its industry. For example, cutting-edge firms and tech companies tend to have angular logos to convey speed, while service-oriented firms have rounded logos to provide a sense of service and trust.
Logos are the chief visual component of a company's overall brand identity. The logo appears on stationery, websites, business cards and advertising. For that reason, a well-designed logo can contribute to business success, while a substandard logo can imply amateurishness and turn off potential customers. However, a logo should cohere well with other aspects of a company's visual presentation: No logo, however well designed, can look good when surrounded by contradictory graphical elements or inconsistent fonts. This is why a logo is the basic unit of a larger brand identity that includes company fonts, colors and document-design guidelines.
Return on Investment
As consumers grow to know, like and trust a specific brand, they are more likely to respond positively to successive encounters with a logo--potentially leading to increased sales or improved mind share within the target market. In addition, a well-designed logo implies a degree of professionalism and competence that could help steer potential new clients toward selecting the business rather than a competitor with no or substandard logos.
Common Mistakes
Small businesses often play it fast-and-loose with logos, paying insufficient attention to their proper size and positioning and surrounding them with materials--including clipart--that compete with them visually. Avoid re-creating different types of logos for specific purposes (e.g., letterhead and business cards) or having similar-but-not-identical versions for print and online purposes.
References:
http://smallbusiness.chron.com/importance-logos-business-577.html