A Social Media Marketing Agency is either a specialized marketing agency that only does social media marketing or any marketing or public relations agency that performs social media marketing tactics for their clients.

Some Social Media Marketing agencies specialize in only one platform such as a Snapchat or an Instagram specific agency.

Others might only specialize in one type of marketing on a platform such as a Facebook Advertising agency or a Reddit promotion agency.

Still others might have a vertical social media specialty such as a concert social media marketing agency or a restaurant social media marketing agency.