Here's why:
* Noun: It refers to a specific thing, a collection of online platforms and tools used for communication and social interaction.
* Phrase: It's a group of words that act together as a single unit. In this case, the phrase is made up of the adjective "social" modifying the noun "media."
While "social media" might sometimes be used as an adjective (e.g., "He's a social media influencer"), its primary function is as a noun.