Other than your grades and act/sat scores, which are provided through official transcripts and reports, your alo will, or should, verify everything that is on your application that is significant. If you say you play varsity sports, I'm going to verify it. If you say your the class bp, I'm going to verify it. If you say you're in the church choir, I'm probably not going to verify it. If you say you had summer jobs, I'm probably not going to verify it. If you say you received some prestigious award, I'll probably verify it.
A lot depends on the applicant, the claim, and the size of the town. Fore, I can usually do a Google search or search online newspapers and verify just about anything about a wyoming applicant. We are small town America. Everybody knows everything about you. My applicants know right away that they better be truthful on their application. If you lie about achievements, I will know and it will show in my review of you.
But for those who can easily be lost in the crowd, your application is where you need to brag about yourself. This is not the time to be shy. When I or the academy look at your application, we should know EVERYTHING about you. Good and bad. Be proud of all the good things, and be humble and show you grew and matured from the bad things.