Introduction to Highers
Highers are part of the "Higher Still" program, which was implemented into the scottish cirriculum in 2000. Within this program, you also get Access 2/3, Intermediate 1, Intermediate 2 and Advanced Higher.
Before the new program was implemented, you simply had standard grade, higher grade and CSYS (Certificate of Sixth Year Studies). But, the SQA found that too many people were failing these courses, so the Higher Still was born.
A typical Higher has 3 units (normally 40 hours long per unit), and after every unit you sit a NAB test. A NAB test is just like an end of topic test that you may have sat at standard grade, except that it is normally set at C level (Higher). You must pass all 3 and the final exam to get an overall award. There's no doubt that you've probably been told all of this, but make sure you know all the units for each subject, and the nature of both NABs and exams before starting.