The Reviewer badge description is:
1000 reviews, over 200 actioned
What does actioned mean in this context please?
To review a post is to press "review answer/question" on a post on the review page (which makes the post expand so that it may be reviewed). "Actioned" refers to having done any of the following on a reviewed post:
When you get the Strunk & White badge on a site you get a tracker on the review page which tracks reviews and actions on reviews. On Stack Overflow it looks like this for me:
The badge Reviewer and the review tracker are due to a recent change, see Have the review link appear for anyone with the Deputy badge.