Facebook recently modified their search parameters, retroactively making all posts marked "public" fair game for search results.
What does this mean for you? Your public information will be easier for folks outside of your network to find.
For example, a stranger searching on Facebook for 'community service opportunities' might stumble upon the picture you tagged of yourself helping at a food drive, depending on how your picture is described when it was originally posted.
Having your information appear in a stranger's Facebook search results isn't necessarily positive or negative. What does matter is that you are aware and in control of your public-facing information online.
The Cornerstone standard is to restrict privacy settings to "Friends only" across your social media profiles, and then to individually select which posts you'd like to make public.
Go to 'Settings' in Facebook...