There are three major systems of grading black tea and the grades refer to the size and state of the leaf.
The most common incorrectly used grade is OP. This refers to one of the grading categories of tea “orange pekoe”. Often people ask for an orange pekoe tea and they relate it to the flavour but in fact this has nothing to do with flavour, or oranges. It is only the grade of the leaf size.
There are many other grades such as “P” for pekoe and “F” for fannings, which is the size of the leaf commonly used for tea bags. Usually the more letters the better quality the tea.
There is a lot to learn about grading and this varies in different countries. The main thing to remember, which is more important than the grade, is to understand the flavours and aromas of tea as this is what counts the most.
You can have high grades of tea as far as leaf-size goes and yet they may have been poorly processed, so unless you taste the teas you will never know.
FTGFOP is a grade that has been jokingly referred to as “Far Too Good For Ordinary People”.