Data types are the types of things which Logo can work with. Data types is a shortcut word for types of data. Traditionally Logo identifies two very general types of things: words and lists. Although Elica can identify these things, it has no knowledge how to work with them. This is as if you can read a foreign language but cannot understand it.
WORDS are the most basic type of things. You already know what a word is as long as you know how to identify words in a program. This is exactly what Elica does when it analyzes your instructions. Some words contain letters, others contain digits that form valid numbers
LISTS are sequences of words. The firstword must be [ and the last one must be ]. All words in between are called elements of the list. The list [A B C] contains three words. A list that contains no elements is called an empty listand is written [].
It is possible one or more of the elements of a list to be lists by themselves too. In this example
[A [B C] D E]
the second element of the list is [B C] and is a list by itself. Lists are important for Logo because all instructions you give to Logo are written as Lists.