This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Rather than ask for a detailed explanation of a general topic, I suggest you go out to the web and read some of the many resources (like this tutorial) already available about this and other topics that may be of interest to you. If you have any specific questions or doubts, come back here and we'll see if we can help.