There are many, MANY sites out there devoted to helping writers on the road to creating their content. There are just as many sites that have compilations of these resources. In case this is your first stop on the road to internet research about writing, allow us to point to a few for you. (This post may be updated as sites come and go, or resources grow.)
editing
The Semicolon, aka. the Supercomma
There is a form of punctuation called the semicolon. (It’s the one that looks like a comma with a period stacked on top of it.) In my time as a copyeditor I’ve slashed out more semicolons than I care to count, usually due to overuse or misuse. I prefer to think of the semicolon as a supercomma. It helps me to remember the proper usage of the beast.