A logo is a symbol, design, or phrase used to identify a company's products or services and distinguish them from those of others. This falls directly under the definition of a 'trademark'.
A Trademark protects brand names and logos used on goods and services.
Copyright protects original artistic and literary works (like books, music, paintings).
A Patent protects inventions.
An Industrial Design protects the aesthetic shape or appearance of an article.
To prevent others from using its logo, the company must register it as a trademark.