Both – Either – Neither

Here are some rules to remember when using BOTH, NEITHER or EITHER.

Both = this AND that
Either = this OR that
Neither = NOT this and NOT that.

Both is used with 'and'

e.g.: "Emma and Megan both went to the party."

We don't usually use this with a negative sentence, but use neither instead.
e.g.: "Both of us don't swim regularly." WRONG.
"Neither of us swim regularly." MUCH BETTER!

Either is used with 'or'

e.g. : "Do you want either chocolate or crisps?"

We often use neither with 'nor', although this is quite formal.

e.g. : "Neither Caroline nor Marguerite worked for EC during the world cup."

Be careful not to use neither with another negative

e.g. : "I don’t want neither chocolate nor crisps." WRONG. We cannot have a double negative!

(from English channel, ECE)