How readers will access an item impacts the potential readership. Many academic items are purchased through costly subscriptions, and while they provide access and reach, their cost may exclude readers who do not have access. Open access is a broader idea to provide academic information free of cost to readers. That being said, one must usually pay an article publication charge (APC). An APC is a fee charged to authors to make their work available as open access (OA).
DOAJ (Directory of Open Access Journals) is an organization dedicated to providing free access to scientific information. Check their site for reputable journals.