BESIDE VS BESIDES
‘Beside’ is a preposition and means ‘At the side of’ or ‘By’.
Who is slim girl sitting beside Hob?
‘Besides’ is either a preposition or an adverb.
As a preposition, it is used rather like ‘As well as’, whenever we have to add new info to what is already known.
Besides math, we have to study chemistry and physics. – We have to study chemistry and physics as well as math.
Who was on the trip besides John and Mary? – I knew about John and Mary, but who else was on the trip?
As an adverb, it means ‘Also’, ‘Moreover’, or ‘As well’ and usually goes before a clause.
I don’t like her lifestyle; besides, she is too superior.
It is too late to dine out. Besides, the restaurant is being crowded.