Forms
I'm involved with a charity which needs to send out forms which can ideally be filled out 'on screen', having text and 'click' boxes, and emailed back. We have 'inherited' a series of MS Word-based forms.
Currently a significant number of 'customers' use only (not-so) smartphones or tablets and either don't know about or have not installed apps to handle MS Word docs. For these we send out fillable pdf forms. For those with 'proper' computers, Windows, Linux or Mac, we have no issues.
What is the best 'universal' medium? If pdf (preferred by us), can all smartphones and tablets handle these without upgrades?