The letter grade at one school may or may not be the same as the letter grade scheme at another school. Some answers to the inconsistencies here.
Most schools use letter grades these days. But not every school uses the same letter grade scheme. This can cause problems when it comes time to send transcripts off to college admissions offices. The A at one school may not be equivalent to the A at another school.
The most common grade scheme is the following:
F Below 60
If your school uses a variation of this scheme, then be sure to send a key or explanation sheet attached to each transcript. Failure to do so could cause mis-interpretation of students' results.
How does this tie in with GPA?
GPA or Grade Point Average is numerical equivalent of all your letter grades totalled and averaged. The numerical equivalents for letter grades are as follows:
A = 4.0
B = 3.0
C = 2.0
D = 1.0
F = 0.0
So, in theory if an A is 4.0, an A+ is higher. At some institutions that is the case. To put grades into perspective most graduate schools will require a 3.0 GPA for admission. American public schools set the benchmark at 1.0 for graduation.