In general, there are three types of resources or sources of information: primary, secondary, and tertiary. It is important to understand these types and to know what type is appropriate for your coursework prior to searching for information.
It's sometimes difficult to distinguish among these three types and they do vary by discipline and subject..
Reports original research or experimentation
Critically surveys and analyzes the current state of published research on a particular topic; doesn't include original research
Describes one or more theories, frameworks, models, etc. and tends not to include empirical data
Makes you an informed researcher/applicant
Provides perspective by situating your work within the knowledge base (theory & practice) of your field
Supports your research idea/proposal or identifies a gap needing further research
Provides ideas for research design; for example, quantitative or qualitative approaches or instruments to use
Provides credibility to grant proposals