There is a primitive type in Java that tells the truth and nothing but the truth. It's called boolean.
Often times we don't really know how many items an array will have down the line. If that's the case, it might be a good idea to use an object called ArrayList.
HashMaps are collections of key-value pairs. In a way, they're like dictionaries: every key points to a value.
A method is a named block of code that serves a specific purpose. In order to call a method, we use its name followed by parentheses.