15 question types

Which question type fits which job.

Choice

Single choice: the classic question with round buttons, only one answer allowed.
Multiple choice: checkboxes, respondents can tick several answers.
Dropdown: one answer from a long list without taking up much space.
Open list: respondents type several answers of their own.
Matrix: a grid of rows and columns, handy when several items are rated on the same scale.
Ranking: respondents put options in order of importance.
Rating scale: a score on a scale, for example from 1 to 10.

Short text: a one-line answer.
Long text: a detailed answer or comment.
Respondent name and respondent email: these answers are shown separately in each respondent's report, so you can tell who answered.
Address: a postal address split into fields.
Date: a date picked from a calendar.
File upload: respondents attach a file, such as a CV or a screenshot of an error.
Text block: not a question, but an explanation or a heading.

If you want to compare answers on a chart, use questions with options rather than text fields.
Many ratings in a row on the same scale: one matrix instead of ten separate questions.
Applications and feedback: name, email and a long text field.

Can I make a question required?

Yes, it is a setting in the question form: respondents cannot move on without answering it.

Where are uploaded files stored?

On our servers. You can see them in each respondent's report, and the total size of uploaded files is shown in your account settings.