Preposition: This is the most common usage. It indicates location or position, often meaning "next to" or "at the side of."
* Example: "The cat sat beside the fireplace."
Adverb: This usage means "near" or "nearby."
* Example: "The dog barked beside himself with excitement."
Conjunction: This usage is less common and means "in comparison with."
* Example: "The new car looks quite ordinary beside the sleek sports car."
To figure out the part of speech, consider the context of the sentence. Look at what words "beside" is connected to and what role it plays in the sentence.