Big companies make their logo in a unique style. There is always a hidden meaning or a message that is portrayed through the logo. A proper logo should be able to tell what the company is about, its products and sometimes the area that it is based in.
The concept of a logo actually dates back to the pre-historic age, when a pictograph was used to depict objects. The Egyptians later used pictographs and developed the "hieroglyph". They were masters of telling stories and historic events just by hieroglyphs.