A PDF file is sometimes too large to send in a regular email. When this happens, you won't be able to send it as an attachment, so you'll want to find another way to send it. With a PDF, you can usually compress it in a zip file, just like any other large file. This is the easiest way to compress a big file, and your receiver can unzip it when it gets where it's going.
Right click on your desktop and choose "New Folder." You can name it anything you'd like.
Drag the PDF file into this new folder.
Exit out of the folder if you are inside it. Then right click on the folder. Choose "Send To" and then "zip File." The program will make a duplicate copy of the folder with the PDF inside of it, but it will be a zipped, or compressed, file.
Attach the zipped file to your email, just as you would any other type of attachment.