A single-level bulleted list, a single-level numbered list, and a multilevel bulleted list.
Lists are very useful things to have in a document. From summarizing information to making it easier to understand and digest, lists have many uses. There are numbered lists and there are bulleted lists. If you have a sequence of information, a numbered list is essential. If you're not worried about sequence, a bulleted list might be better.
Lists can be single-level or multilevel: Single level (or single layer) means that all items in the list have the same hierarchy and indentation; multilevel means that there's a list within a list. You can see the difference in the picture.
This lesson is all about simple lists, that is, lists of only one level or layer. Multilevel lists are discussed in the second lesson.