What is the name of the dot over 'i' and 'j'?

First off, "YOU" is not a letter. I assume you mean "U" and dots above the letter "U" could be a number of things. ü, ù, ú, û, ǚ, ǘ, or ǖ. I'm going to assume YOU (which is not a letter) mean either ü, ù, or ú. The last two have ACCENTS. (I assume you know what an accent is.) The first has an UMLAUT. google it.