You will encounter many types of articles and it is important to distinguish between these different categories of scholarly literature. Keep in mind the following definitions.
Peer-reviewed (or refereed): Refers to articles that have undergone a rigorous review process, often including revisions to the original manuscript, by peers in their discipline, before publication in a scholarly journal. This can include empirical studies, review articles, meta-analyses among others.
Empirical study (or primary article): An empirical study is one that aims to gain new knowledge on a topic through direct or indirect observation and research. These include quantitative or qualitative data and analysis. In science, an empirical article will often include the following sections: Introduction, Methods, Results, and Discussion.
Review article: In the scientific literature, this is a type of article that provides a synthesis of existing research on a particular topic. These are useful when you want to get an idea of a body of research that you are not yet familiar with. It differs from a systematic review in that it does not aim to capture ALL of the research on a particular topic.
Systematic review: This is a methodical and thorough literature review focused on a particular research question. It's aim is to identify and synthesize all of the scholarly research on a particular topic in an unbiased, reproducible way to provide evidence for practice and policy-making. It may involve a meta-analysis (see below).
Meta-analysis: This is a type of research study that combines or contrasts data from different independent studies in a new analysis in order to strengthen the understanding of a particular topic. There are many methods, some complex, applied to performing this type of analysis.
Most databases allow the use of AND, OR and NOT to broaden or narrow and search.
Truncation: You can use an * at the end of a word stem to broaden your search to include related terms. For example, to search for child, children or childhood use the search term child*
Putting quotes "" around words allows you to search for a phrase. For example, searching language development, without quotes, finds records with both the word 'language' and 'development' somewhere in the record. Searching "language development", with quotes, only find records with the phrase "language development".
Example: How does bilingualism affect language development in children?
NOTE: When you begin doing advanced searching in a new database, look for the Help or Information sections to determine how that database works, and how it may differ from other databases with which you are familiar.