Semiotics

Semiotics is the study of signs; their meaning, significance and purpose. In day to day life we are bombarded with images (or signs) that may order, direct or explain without the use of much text or none at all. In a society where advertising is constantly surrounding us we have learnt to connect certain feelings, emotions, and desires with the use of specific visuals (often subconsciously). Advertisers can use this to create catchier shorter methods of passing information to the consumer. It also allows for them to catch their target market quickly and efficiently.
Not all semiotics are linked so directly to advertising. Colour is a good example of the use of semiology. For example blue representing cold and red as hot is found on almost all taps internationally. Road signs are also designed to communicate without the need for text or lengthy explanation. Drivers quickly become accustomed to road signage.
Of course it could be that a semiotic technique used in one country could change or loose meaning (importance) in another for example the use of a particular colour as bad or dangerous. However through our ever more connected world most common signs (green man crossings, buttons on electrical equipment) can be used across the world, allowing for better trade and improved communication between cultures.

References
http://www.aber.ac.uk/media/Documents/S4B/sem02.html
Mythologies - Roland Barthes
http://www.isisemiotics.fi/