Often you will be tasked with finding different types of resources for your assignments. A professor may say, "I need you to find at least one primary source and 3-4 scholarly, peer-reviewed journals on your topic." First step is understanding what kinds of resources fall into these categories. Next, you find them.
Context and intent of the resource is very important. In short, was it written by the person(s) who witnessed or created the source or is it a review, summary, interpretation of a source? Option 1 is primary and option 2 is secondary in most cases.
These sources are first-hand accounts of events or evidence without any interpretation, comments, or filter. Primary sources show the information, research, or event as the original material; they display original thought, or report on new discoveries, or share new information.
Secondary sources are reviews, accounts, summaries, or interpretations of the event or evidence (primary source) after they occurred. Normally these kinds of materials add comments or summarize events or evidence with some insight.
Tertiary sources distil primary and secondary sources. Think of them as a list or reference material or repackaging of an event, idea, or person in a more compact way.