It is important to make users aware of required fields upfront. This should prevent them from making submission errors and having to backtrack through a form to fix such errors. But what is the best and most accessible way to indicate required fields? This article aims to explain exactly what’s required.
This is a well-established and widely understood convention but it’s still good practice to include a note at the beginning of the form to explain that asterisks denote required fields.
I don’t consider a form that uses asterisks but has no explanation of what they do sufficient to meet Labels and Instructions.