Even if you have done business with a company or organization, you do not have implicit permission to use their logo for your own promotion in your marketing materials.
Company and organization brands are the visual image to the world in color, logo, and use of language. Each brand has a different purpose, though strength, integrity, and consistency are some of the key elements underlying most brands. The logo is the distilled visual representation of their brand.
A logo is “the mark” in design. There are several different types of marks. A logo mark is the graphic symbol. A logo type is a logo in a specific type face and color combination without a graphic symbol. A combination mark is the graphical symbol and a specific type. All of these are protected from use for promotion outside the actual company.
To protect their brand, many companies and organizations trademark their logo.For unauthorized use of their logo, a trademark gives extra legal protection to the company. A logo not yet trademarked, is still protected by copyright laws. Side note, they also often trademark their tag lines as well.
If you are not a part of that company or organization, using a logo by itself to represent you or your work is a violation of the trademark or copyright, and can be subject to legal action.
In order to use another company’s logo or company/organization’s identity to augment your identity, what you need is written permission. Yes, those client pages, that you see filled with logos on some websites, should all have written permission to use the logos that they show.
Legal permission for logo use can be written into a contract between businesses or businesses and contractors. Often legal departments will not allow that permission in a contract.
Using a logo or mark to link to a website representing that company is acceptable, as long as you do not imply that this company endorses you, without getting their permission.
Logo Mantra: Treat logos with respect.