Adobe's PDF is the de-facto standard for sending non editable documents, because everyone has or can get a free PDF reader.

But creating them is a different matter.  Adobe want you to pay US$49 for their utility to create PDF files. DONT do it! 

Adobe Acrobat Professional sucks.  Really.

Its as big and bloated as anything Microsoft have produced.
    It continues to create folders  (My Ebooks) that 99% of people will never use.
    It adds usless folders and shortcuts to your programs menu. Internet printing? - If I want it I'll look for it. Dont add things to my computer unless I ask you to.
    It adds programs that run at startup and in your system tray to try and disguise the fact that it's as slow as a sick  three legged dog to load.

The free Acrobat Reader works, but is also slow and bloated.

I could go on.  But instead try this:
 Foxit PDF reader - small, clean and much faster than Adobe's Acrobar reader.

And if you want to create PDF files this site will cover the needs of most people:  Create PDF's from Word or HTML,  There are free and paid versions available...
http://www.expresspdf.com

There are other free PDF creators about. They may not have as many features you'll never use as Adobe's but they don't try to take over your PC either...