This user knows that "there's" with a plural subject is a pervasive grammatical error. There'sThere are too many people making this mistake. Don't be one of them.
their there they're
This user thinks that there are too many people who don’t know that they're worse than their own children at spelling!
its
This user understands the difference between its (of it) and it's (it is or it has).
A, B, and A and B
This user prefers to use the serial commaonly when its omission can be confusing.