why is there a dot on top of the letter “j” and the letter “i”?

“I” has been adapted in a number of ways. The second one I’ll list is the one you’re really interested, but some of the other stuff may help to understand what’s going on (or simply be interesting, I hope).

1) First, note that the original letter is simply I — J was a late alternate form used in certain situations, such as double-i at the end of a word. I believe the point of forms like “ij” was to make clear that the additional stroke was not just a stray mark. (Note that BOTH forms could denote either the vowel or consonant –the were simply used in different situations within words. The use of “I” for the vowel use and “J” for the consonant came much later. The story of the “bi-forms” u/v is similar.)

) In fact, the only form at first was the “capital I” (since only the capital forms existed). When the ‘minuscules’ or ‘lower case’ letters developed, the result for I was a very short vertical stroke (“i” without the dot).

Amidst the short vertical strokes of other letters (such as n, m) the small i might easily be missed or misread (e.g., turning an n into an m). So

an oblique (acute accent) mark was written over the i to distinguish if from other vertical strokes. Later, with the invention of the “Roman typeface” (straight up and down vs. italics) the mark was reduced to a dot. This mark, by the way, is called a “tittle” (used in the biblical expression “jot and tittle”).

As an alternate form of i, j simply followed suit.

3) On a related point – when the English word “ic”/”ich” (the form still found in German) became “i” there was concern that a handwritten i all by itself would be interpreted as part of an adjacent word . The solution to this was to substitute the capital “I” (ca. 1250). (So, contrary to the imagination of some, it had NOTHING to do with vanity! Incidentally, the form “O” as in “hear me, O Lord” probably came about the same way; note that the slightly different form “oh” [“oh dear!”] does not use the capital, except of course at the beginning of sentences.

— from The Barnhart Dictionary of Etymology

http://www.alt-usage-english.org/excerpts/fxwhyisi.html

The Midas Well Mindless Self Indulgence The Misfits

The Latin alphabet does not have all the letters or all the sounds that English has. English is a Germanic language and some of their sounds are harder than Latin sounds.

A J is a hard I, like in the word Jack.

These sounds came into Latin after the Germanic invasions.

Classical Latin does not use them, Catholic (or later Latin) does.

that can be said about all letters .. why does letter A look like letter A or letter B look like that… cuz the person who first made up the letter was just being creative and thats what he came up with.

So that we don’t confuse them with ls or ts. You know for people with bad handwriting.