Articles in peer-reviewed journals have been assessed before publication by subject experts. This means they are the "gold standard" in academic articles - the top journals in any field are highly likely to be peer-reviewed. You will be normally be expected to use peer-reviewed journal articles in your assignments.
Open access articles are free for the user to read - unlike the majority of articles in the academic world, which are published in journals which cost to view articles individually or require a subscription to the journal. One of the huge advantages of working or studying at Trinity College Dublin is the breadth of journals we subscribe to via the Library - we are paying for your access - but that doesn't help those at institutions with less resources, or independent researchers working outside an academic body.
Many sponsors of academic research now stipulate that the work that flows from their funding must be made available via open access, although that doesn't necessarily preclude publishing the work first in a non-open access journal. For example, a healthy proportion of research published in the traditional journal literature is available in "institutional repositories" where the parent institution makes its researchers paper accessible (such as TCD's TARA, the content of which can be along with other Irish institutions in RIAN). These are normally versions of papers called "pre prints" - the content of the paper is the same, but without the formatting the journal will apply.
Important to note, that while more journals are making their content at least partially open access directly within the journal website, many demand a hefty fee from the author to do so.
Want to know more about open access or the scholarly publication process? Contact our experts in the Library - Research Information Systems and Services. They can advise on research communication, dissemination and reporting and on maximising the impact of your research.