What are social media platforms?

A Social media platform is a website or application that people can access social media's functions.

There are many social media platforms available. Here are five different types of social media applications for your reference:

• Facebook (https://www.facebook.com); Facebook is an American online social media and social networking service platform. It was launched on 4 February 2004, it has 2.8 billion monthly active users (as of 2020) and it is available in 111 languages.
• YouTube (https://www.youtube.com/); YouTube is an online video sharing and social media platform owned by Google. It was launched on 14 February 2005. YouTube has 4 products: YouTube Premium, YouTube Music, YouTube TV, and YouTube Kids.
• Instagram (https://www.instagram.com/); Instagram is an American photo and video sharing social networking service platform. The initial release date is 6 October 2010. It is available in 32 languages.
• TikTok (https://www.tiktok.com/ or https://www.douyin.com/); TikTok (Douyin in China) is a video-sharing social networking service owned by a Chinese company ByteDance. The initial release date is September 2016. 
• WeChat (https://web.wechat.com/); WeChat is not only an instant messaging and social media platform but also a mobile payment app. WeChat is developed by the Chinese company Tencent, the initial release date is 21 January 2011.

[References and related articles]

[1] Wikipedia. (n.d.) Facebook. Retrieved 28 May 2021 from https://en.wikipedia.org/wiki/Facebook.

[2] Wikipedia. (n.d.) YouTube. Retrieved 28 May 2021 from https://en.wikipedia.org/wiki/Facebook.

[3] Wikipedia. (n.d.) Instagram. Retrieved 28 May 2021 from https://en.wikipedia.org/wiki/Facebook.

[4] Wikipedia. (n.d.) TikTok. Retrieved 28 May 2021 from https://en.wikipedia.org/wiki/Facebook.

[5] Wikipedia. (n.d.) WeChat. Retrieved 28 May 2021 from https://en.wikipedia.org/wiki/Facebook.

What is social media?

Social media are technologies or applications that allow users to create and/or share information, videos, images, etc. in interactive ways.

Users are the social media content producer. Anyone can sign up for a social media account as long as they have internet access. 

A user can use social media account to share stories, do marketing, attract audience attention, and promote sales.

I think the 2 links as follows provide a good explanation of social media:

https://communications.tufts.edu/marketing-and-branding/social-media-overview/

https://en.wikipedia.org/wiki/Social_media

They are not only made plain explanations but also use detailed examples to help an understanding.