People do not understand everything when they are born, but have to learn everything so that they are able to understand. Take learning English for example; not everyone can understand it, but some non-native speakers can use the language very well. This is not only the case with English, but also other subjects. Therefore, during the learning process, one might find that some people can learn every subject or several subjects very quickly and well. On the other hand, some people have problems learning. Therefore, many researches try to find how learners go about learning something, what makes learners successful at learning something, and why some people are more effective at learning than others. As Williams & Burden (1997) point out, that can only be answered by investigating learning strategies.