You can add a variety of different types of questions to a category:
In response to a question (that may include a image) the respondent chooses from multiple answers. There are two types of multiple choice questions - single answer and multiple answer.
In response to a question (that may include a image), the respondent types a word or phrase. There may several possible correct answers, with different grades. Answers may or may not be sensitive to case.
From the student perspective, a numerical question looks just like a short-answer question. The difference is that numerical answers are allowed to have an accepted error. This allows a continuous range of answers to be set.
In response to a question (that may include a image), the respondent selects from two options: True or False.
A list of sub questions is provided, along with a list of answers. The respondent must "match" the correct answers with each question.
These very flexible questions consist of a passage of text (in Moodle format) that has various answers embedded within it, including multiple choice, short answers and numerical answers.
From the student perspective, this looks just like a Matching question. The difference is that the subquestions are drawn randomly from Short Answer questions in the current category.
A Random question in a quiz is replaced by a randomly-chosen question from the category that was set.
This is not a real question. It simply prints some text (and possibly graphics) without requiring an answer. This can be used to provide some information to be used by a following group of questions, for example.
Calculated questions offer a way to create individual numerical questions by the use of wildcards that are substituted with individual values when the quiz is taken.
In response to a question (that may include an image) the respondent writes an answer in essay format.