Online Marketing 101 - no matter which source you are referring to, everyone's talking about the importance of video content.
Adobe Spark is a free programme, available to all. If you are a Creative Cloud member you have the ability to remove Adobe Spark branding from the end of your video (using the web app, apparently it will also be available on the iOS app in the future - see link at the end of this post), but as a free option for creating online videos a tag at the end of your video is better than not getting a video out there.
Personal use is also a valuable option - I created a compile of smart phone videos from a family event and sent the one video out to family members instead of attaching a bunch of videos and photographs from my phone. It's a much easier viewing option than opening individual files, and the addition of royalty free music that is included with the Adobe Spark app was perfect.
Yes, there are limitations - if you are familiar with more advanced/paid options for creating videos the lack of options for things like transitions between clips is disappointing, but hey, if you are tempted to try video for business or for home, you can't really go wrong here.
When you open the app you'll see that there are three options: Page, Post and Video. I've only used the video so far, but if you're interested in creating a social media post with Adobe Spark head straight over to 3:00 on this video from dottotech to see how to do it! He also show the video action at approx 9:20.
For a demontration on Adobe Spark Page, here is Adobe evangelist Julieanne Kost to talk you through it.