The vast majority of people under the age of sixty have access to social media and even if they do not consistently post on their page, they will be able to be part of groups in the local community and follow posts about local events. Although the idea of using a parish noticeboard situated in a prominent position has been used for years this is becoming a much less effective way of communication largely due to the fact that fewer people are walking to the local shops than in previous times and therefore they are not seeing the notices placed there.
If you want to publicise an event a better way of reaching the community is through a social media community page. Some of the members act as administrators on the page and monitor the posts and comments before allowing them to be uploaded removing any that break the page rules. People can request to join the group and, in some groups, have to wait to be accepted before they can begin posting. This method of communication is useful as it can convey new information quickly for instance in the case of roadworks or a postponed event. If you can offer a service to your local community it can be advertised on the local community page too.