It is easy to confuse ‘beside’ and ‘besides’, but they are not one and the same thing. ‘Beside’ is a preposition, whereas ‘besides’ works as both a preposition and an adverb, and although ‘ besides’ is sometimes used in place of ‘beside’, they have distinct meaning.
‘Beside’ means ‘by or at the side of’. For example: He stood beside his new car proudly.
As a preposition, ‘besides’ means ‘in addition to’ or ‘ apart from’. For example: What are you working on besides the research project? As an adverb, it means ‘ furthermore’.As in, ‘ He was not selected because he did not have a good grasp of his concepts. Besides, he did not seem very keen.’
As mentioned above, the distinction between the two words is sometimes ignored. ‘ Besides’ can never mean ‘at the side of’, but ‘ beside’ is often used in place of ‘ besides’. This can lead to misunderstanding, though; the sentence‘There was no one beside him in the hall’could mean that ‘ he’ was all by himself, or that there was no one next to him.