One of the classic colours is Black. It represents power, sexuality, elegance, authority. Because of that we can notice that suits usually worn by businessmen, leaders or some other important persons are commonly black. However, black colour also is very close to drama, death or sadness and is mostly connected with depression and unhappiness.
Other colour from "classic" series is Red. It's the most noticable colour, which means danger, passion, energy, aggressiveness. Red is the most emotionally intense colour and stimulates a faster breathing and heartbeat.
The opposite colour is Blue. It suggests trust, coolness, reliability, serenity, protection. Because of these features blue is often considered as a business colour. Brown is an earth color and quite similar to blue because it also associated with stability, security, politeness, helpfulness that is nevertheless important in buisiness world.
The most positive colour is Yellow. It suggests creativity, cheer, happiness, hilarity. It stimulates the intelect and enhances concentration. It is said, that yellow is the colour of optimists.
Though colours have different meanings in various cultures and countries, they are generally used in logos to convey a specific message and the basic kowledge of colors can be fitted on a various situations, so it is useful to know about the influence of colours. For example, it is widely known that the best colour duet to use on advertisements, mass-media and social commercials is bright yellow and black. It amazingly stimulates human's mind and extraordinary catches attention. So, gives the best effect. And it's only one little drop in the sea of colour affection.
Sources of information:
http://iit.bloomu.edu/vthc/Design/psychology.htm
http://ezinearticles.com/?Choose-and-Use-the-Best-Colors,-The-Psychology-of-Color&id=12855
http://www.apartment-ideas.com/psychology-of-colour.html