When you make a field required, people must enter an answer to the field in order to submit their entry. When someone tries to submit an entry without filling out a required field, we highlight the problematic fields and display an error message to let them know the field is required.
You can apply this setting to any field type.
To require an answer to a field:
Required fields are marked with a red asterisk next to the field label. There's no way to change the color of the asterisk.
The Required setting works a little differently for Dropdown fields. Learn more: Dropdown Field
If you notice in your entries that people were able to skip required fields, there are a few things that may be happening: