Which companies own social media platforms?

Which companies own social media platforms?

The question has been a popular one on Twitter, with a wide variety of people answering differently. Some say Google owns YouTube, Microsoft owns LinkedIn, Facebook owns Instagram and WhatsApp. Others think that Amazon is the owner of YouTube and Facebook, while Apple has Inc. Magazine as their property. One person believes that Snapchat is owned by Snap Inc., not by SnapChat hardware company Spectacles...

In general most people believe that these companies own their platforms in some way or another with the most likely being LinkedIn being owned by Microsoft and Amazon owning Youtube for example.