Your phone's battery power has gone and you desperately need to send a text message so you ask to borrow a friend's phone. It is a totally different make and model to the phone you're used to and you have to fiddle about with it for a few minutes, but eventually you get there in the end. The ability to do this on phones and other products is down to the clever use of icon design.

The use of icons in user interface products, websites or software programs define image and brand, but also provide a set of functions and almost act as the language of the product. This is why it is important for a company's language to speak with clarity to your audience and be easy to interpret.

Companies with an international market take the time in planning and thinking hard about how they will get their message across to the user. A mobile phone company could have one person in Japan using one of their handsets and another in Germany with the exact same model. Both users will be able to identify with the product and easily interpret it.

Issues to consider when designing icons include cultural references. Using an iconic red post box to indicate 'mail' would have no problems in being interpreted in the UK, but not necessarily overseas - one person's letterbox could be another's dustbin.

This is also the reason why the use of text is minimal, and sometimes non-existent in icon design, as international audiences would not necessarily gain the desired understanding of the product's function.

Companies have to undertake thorough research particularly if they want to be culturally sensitive. For instance, the use of some animals as icon images may not translate well, as do some images of people and hand gestures.

At the same time, some cultural references can be hidden in the design and function as a catalyst which connects with different cultures. They can sometimes trigger the awareness of the cultural meaning of the design's message and context and can connect different levels of information.

Metaphors are a vital tool for representing function and purpose to the user via icons and the use of a metaphor will allow the icon to be understood quickly. This can achieve optimal operation of the application it is designed for. If thought is put into the design, cultural references can be implanted into a company's designs, which turn disparate data into meaningful information.

Adopting widely understood images with make your application easier to use. For example, most people interpret a green cross as first aid or medicine. When you're on holiday abroad, you never have any problems recognising the local chemist do you?

If you're brave you could attempt to create your own iconic symbol, such as the infamous Apple Inc logo. It uses the formula of simplicity and easy interpretation. One of the reasons it was chosen was because of the apple being a widely recognised fruit by almost anybody in any country. The company's apple symbol is used and understood today as a function in Apple interfaces and applications as well as a brand logo.

The skill of icon design not only involves graphic design but also considers audience behaviour. You should do your research and present this in unique, consistent and well-understood images. With the help of icon designers you should be able to quickly invent and activate stylish and effective icons, which are recognised by everyone.