Willian的小名：Billy / Bill
Interestingly, when William III ruled over in England in the late 17th century, his subjects mockingly referred to him as "King Billy."
很有趣的一点就是，当威廉三世统治英国的时候，他的臣民就开玩笑叫他“King Billy”（实际应该是King William）

Richard：Rich / Rick / Dick
In the 13th century people used to name people based on how their nickname rhymes.
在十三世纪，人们通过韵脚来取昵称。

比如说以下三组表示的昵称一样：
Will= Bill
Rick= Dick
Rob = Bob

Did you also know that Jack is also a nickname for John, Jacob and Jackson!
你知道，那个时候，Jack是John，Jacob，还有Jackson的昵称吗？
Let us share some common names and their nicknames for both men and women.
让我们分享一下，一些常见男生和女生的昵称。

Elizabeth: Betty, Beth ,Liz
Charles: Charlie, Chuck
Catherine: Cathy, Cath
Anthony: Tony
Deborah: Deb, Debbie
Christopher: Chris

There is a lot of conditions but the most important factor is that your name has to be a long one and you want to make It shorter and easier for people to remember !
取昵称的众多原因之一就是，你希望自己特别长的名字能够短一点，并且能够很容易被记住。