1. Paper recommendation letter: a paper recommendation letter from an American university, written, printed and signed by the teacher. The recommendation form is PDF. You send it to the teacher by email, and the teacher fills it out and prints it out, or prints it out and then signs it. Then the teacher put the recommendation letter and recommendation form together in an envelope, sealed it and signed it. Then the teacher gives you the signed envelope and you send all the materials together. Or the teacher can send it directly to the American university you applied for. I can't see the contents of the recommendation letter all the time.

2. Online push: You fill in the teacher's email when you apply online, and then your work is all finished. The teacher will receive an email telling him that a student asked him for a recommendation letter, and then there is a website in the email, as well as the user name and password to log in to this website. He can log on to this website, fill in his own information, then upload his written recommendation letter to the website, and then fill in the recommendation form online (that is, a form on the Internet, just like you fill in the registration form of BBS). He has filled out all the contributions, and you will receive an email telling you that Teacher XXX has submitted a letter of recommendation to you. I can't see the contents of the recommendation letter all the time.