If you have healthy teeth and gums then the use of mouthwash is optional.
A majority of commercially available mouthwashes are designed to act like a deodorant for your mouth—they will freshen your breath and kill some of the germs. However not all mouthwashes are created equally, some are better than others.
We always recommend opting for formulations which are alcohol-free and contain fluoride as they are gentle on the delicate oral tissues and can strengthen your teeth.