PDF files are not only for reading documents. We can also create forms that users can fill in on their computers and send it back. How we can create such forms?
There are very good professional software tools, where you can create these forms. Unfortunately they are quite expensive. Luckily there are even free tolls. I don’t recommend just search on internet for “free PDF forms”. The result would be tools which are not completely free or might come from suspicious sources. You better take package of office software tools called Libre Office. Part of this package is text editor LibreOffice Writer, which is similar to popular application Microsoft Word. With the Writer you can easily create forms, which can be exported to PDF.
You can find detailed guide for creating PDF forms in Writer on Youtube. For example this one