Other than company name, a logo also symbolizes a company and each company has its own logo that represents its trademark. It should be unique that every consumer can remember.
If you have a good company, every products you have that has logo printed on it. Consumers will have the trust to buy it in terms of performance, taste, quality and etc.
If you are old enough then you had witnessed the logo changes of big companies around the world. In order the company to keep up to a rapid change in our economy, they need to update all the time not only their system but also how the company is being represented.
4) Mozilla Firefox