The punctuation of direct quotations is controversial. Should it be?
“Hello,” he said.
or should the comma follow the second quotation marks as follows?
“Hello”, he said.
You can find more discussion of this controversy on the internet here. The terms "conventional" is used for the first version and the term "logical" used for the second version. The conventional (the first above, where the comma precedes the speech marks) is said to be the version which is normally found and taught in the USA.
However the reason the logical is better is because punctuation marks have a meaning of their own; for example a comma usually indicates a pause. Therefore putting a comma before the quotation should be used to indicate a pause in the speech. How else could it be indicated otherwise?