I could summarize this article that I found and source it and tell you the answer that way, however since you seem very interested in the topic, I am going to provide you with the link for you to read the article yourself. It does contain a lot of interesting information:
I am ready to be rated once you have read the article and find it to be a good response.
Kindest regards ***** ***** hope to work with you again soon. It is an interesting question,
It was a pleasure working with you. I look forward to your positive rating shortly.
Donna Kakonge, BJ, MA, TESOL, LLB, ABD
In order for me to receive credit for this question, you must rate me positively. I look forward to your positive rating.