Engagement
Engagement is a two-way street. The first form of engagement is audience engagement. Engagement occurs not when your audience is viewing your post, but when they are liking it, commenting on it, sharing it and taking action from it.
Most platforms have built in insights and engagement checking functionality.
You can see the demographic breakdown of your followers (to make sure you are reaching your target audience), as well as the number of likes. One of the most important forms of engagement is the number of people who have seen the most versus the number of people who have taken action from it (including likes, shares and comments). If you have a high number of viewers, but low actions taken this could mean that your content is not resonating with your audience.
Alternatively, if your posts are not being seen, consider changing your content schedule. Make sure you are posting at times when your audience is active and include a call to action in your content.
The other form of important engagement is your own. Are you regularly checking your accounts, responding to comments, replying to questions, or just otherwise interacting with your audience?
This makes your branding accessible, credible, and authentic. You want your audience to feel like they can trust you, and if you are online, you are available.