Many different types of word processors can save documents in the PDF format. This means that the documents can easily be shared with others who may have a different version of Microsoft word etc.
Most computers have some sort of PDF viewer to open and read a PDF document. There are plenty of free viewers around. However the cost to purchase an editor for the document can be expensive
If you want the end user to just edit a small part of the document that a PDF form might be the way to go. This will allow the end user to edit pre defined parts of the document without any expensive software.
To do this, design your document in any word processor and export as a PDF.
Open a web browser to www.pdfescape.com and “start now” this will allow you to upload a copy of the PDF document. Using the online tools you will then be able to mark out those areas of the document that you want others to be able to edit. Once completed download the PDF document back to your PC.
Open the document with a free PDF reader (Adobe Acrobat or Fox PDF reader) You will now notice that some areas of the form can be edited and the document can be saved with the changes.