Open access means that information is openly available to everyone instead of requiring a subscription to a publication (either an individual subscription or through a library).
There are several different flavors of open access. Some publications are completely open access, where all content is always freely available to everyone. Others make all content available after a certain time period has passed (for example, 6 months after publication). Some publications may make only selected content available as open access.
Open access publications may charge the author for an article processing charge (APC) to help maintain the publication (since they may not acquire profits from subscriptions).
Why should I consider publishing open access?
Publishing in open access publications means that your work will be more discoverable and, possibly, cited more frequently.
Some funding organizations (the NIH or NSF, for example) require that some or all of a completed work (including data) be published open access, since the funding comes at least in part from taxpayer dollars.
Are there any downsides to publishing in open access publications?
There are no inherent downsides to have your work openly accessible, but it is important to carefully select an open access publication. Some publications advertise that they are open access, but are not true academic journals and are looking to collect APCs from authors for profit. These are often called predatory or pseudo journals. Use Think Check Submitor contact a librarian to help consider whether a publication is a good choice or not.