Interfolio
(interfolio com) is, for our purposes, a confidential letter of rec service.
How it works: become a member. A membership for a year is about 20 bucks. Then, you can make a "slot" for a LOR from Dr. Smith, Jones, and Johnson, in anticipation of their letters. In creating these slots, you have unique identifier forms that will go along with their letters. Before asking for a letter, you will want to create these slots and print out those forms.
So, you get the courage to ask Dr. Smith for a letter. You have created your packet of info to give him. Included in your packet is their unique Interfolio form. It has their name, email, a unique identifier, and, more importantly, YOUR name. When they are done writing a letter, they follow the directions that are on the form. They can log into Interfolio and enter the unique code that will designate the letter to YOUR account. They then upload the letter and you instantly have your letter. Since its a confidential LOR service, you can only see that you received Dr. Smith's letter, but you can't read what it says.
*****on the other side of the spectrum****
AADSAS has LOR matching forms. They are basically scantrons; any LOR they receive, they scan, and it immediately registers to your account. You will want to print these forms off, fill out the info, and then scan them into Interfolio. That way, when you send your letters from Interfolio to AADSAS, you will want to send the LOR AND (can't stress this enough) ANNNNNND the LOR matching form from AADSAS, TOGETHER! That way, when AADSAS gets a letter from Interfolio, they can instantly upload your LOR to your account, without taking 6 weeks to manually process it.
Mailing letters from Interfolio to AADSAS does cost money (like 7 bucks for 5 day mailing). It may seem like an extra step, but its surprising how many school DON'T accept LOR from AADSAS. In that case, you can use Interfolio to send the letters directly the school. If you were to ask your letter writers to send the letters to AADSAS, the letters would be gone forever and you would never be able to resend them to a school if needed.
Also, I was used 6 LORs between all of my schools (which all had varying requirements). AADSAS only lets you upload 4. Using Interfolio, I wasn't limited to the space on AADSAS and, if needed, just sent whatever extra letters I needed to that specific school.
The point to this service is that you have the letters at your disposal, but you are still maintaining the confidentiality agreement of your letter writers. AADSAS and schools readily accept LOR from Interfolio, so its a handy service.
(I tried to make that as simple as possible. Hopefully makes sense!)