Is the article peer reviewed?

There are several different ways to check if an article is peer-reviewed (has been reviewed by subject experts): 

• Start with inspecting the journal's website. Information about their peer review process is often found under headlines such as "Journal information" or "About the journal". Can't find any information there? That does not necessarily mean that the article is not peer-reviewed. There are additional ways to check its peer review status. Also keep in mind that a journal generally contains a number of different types of texts. For example, texts such as editorials, letters to the editor, news and comments may be included in a journal without them having gone through a structured peer review process before publishing.
• Another way to check if an articles is peer-reviewed is to look up the journal in the database Ulrichsweb, which is available in the library's list of useful e-resources. Ulrichsweb contains detailed information about over 300 000 journals of various types. When you have located a journal in Ulrichsweb, you will see a tab called "Additional title details", where you might find information about a journal's peer review status. This is often signaled through expressions such as "refereed" or "peer-reviewed". However, as previously mentioned, keep in mind that, lack of information about the peer review process does not necessarily mean that the journal is not peer reviewed.  
• A third way of investigating whether or not an article has been peer-reviewed is to use the "limit to peer review" functionality available in some databases. Unfortunately, the PubMed search interface does not contain a check box that will help you limit your search to peer-reviewed articles only. Most journals in PubMed are peer review but, to be sure, you will have to turn somewhere else than PubMed (such as the sources and tools previously mentioned). One database that does offer information about peer review status is CINAHL. 

Many articles contain statements such as "Accepted" or "Submitted", followed by a date. In many cases these articles have indeed gone through a peer review process. However, there are no guarantees. It might just mean that the manuscript has been accepted for publishing, without having had to go through a peer review process. One last tip is to contact the journal or publisher directly and ask them whether or not the journal and article is peer-reviewed.