In addition to what has being said, if you are a Java developer, then this article will be helpful for the understanding: https://www.sitepoint.com/how-optional

In addition to what has being said, if you are a Java developer, then this article will be helpful for the understanding: https://www.sitepoint.com/how-optional-breaks-the-monad-laws-and-why-it-matters/ https://www.sitepoint.com/how-optional-breaks-the-monad-laws... It gives a lot of theoretical background, but if you read the article here and already know the Optional-type and then you can skip it and go directly to "A Real World Example".