If you have a PDF document you might want to lock it so that other people cannot copy your content. This prevents people from easily taking your work and distributing it without your permission. To prevent copying of your PDF you need to set a password.
Create the PDF normally in Adobe Acrobat.
Click the "Tools" menu. Click "Protection," "Encrypt" and "Encrypt With Password." Click "Yes" for confirmation if prompted.
Click the "Compatibility" drop-down menu and select an option.
Click the button next to "Encrypt All Document Contents."
Check the box next to "Restrict Editing and Printing of the Document."
Type a password.
Uncheck the box next to "Enable Copying Of Text, Images, And Other Content."