Alphabets and Writing

How many letters are there in the Roman alphabet as used by English speakers?

26, right.

Perhaps I should ask how many symbols?

Without much effort, just with the letter A, I've come up with four different symbols, excluding differences in width to height, serif or sans serif, old style, new style and transitional. As native English speakers we recognize all these symbols as one letter of the alphabet.

So, how many symbols? I don't know. I've never tried to count them. And just think what arguments trying to count them would start! Some would say that the second and forth symbols above are variations on the same symbol.

What constitutes A-ness, or B-ness? Look at this example.

The first and last symbols are B and D. With experience, the next symbols in, moving towards the center, are also recognizable as B and D [Well, perhaps the second symbol is a six(6), it depends on context.] But what of the middle symbol?

B-ness comes from a circle with a line coming down on the left side, D-ness by a circle with a line coming down on the right side, but the symbol in the middle has the line coming down in the middle. Is it a B or a D? There could be some argument that because of the way it is drawn, with the thick and thins lines, that the letter is a badly formed D, but examined as a sans serif, gothic style letter it becomes more difficult.

Of course, context plays an important part of interpreting a letterform:
Is the first symbol an A or a D?

The point of all this is, non-English alphabets, particularly those with a hand written tradition like Arabic, has even more of this kind of Cultural Literacy. Arabic, in particular, has almost always been a hand written form, and its scribes are very proud of their calligraphic traditions. Expect to be confused and remember that their calligraphy is the way they write it, not the way you think it should be. When you see something you don't understand, learn from it.