Having a research question or statement is valuable in determining the source of the information you need. While some information is best found in academic journal articles, other information is found in books, and yet other information is found online. 

General Concepts (definitions, theories, etc.)

Books usually are good sources for conceptual information (i.e., when you need things described in a conceptual manner). If you need an overview of a topic, definitions, theories and theoretical bases, and a description of concepts, books are a great source of that information. However, books are less likely to have specific information or the most recent research findings (although they provide historical overviews of topics). Compared to articles, books have a longer publication cycle, which requires longer periods for writing, editing, publishing, and distribution. Therefore, information in books tends to come out less frequently or older than it would in a journal article or online.

Trends, Latest News Stories, and Things of Popular Interest

Websites on the Internet can provide conceptual information, and they can provide data or other forms of information, such as news articles, government or public service reports, or sources of information that are made readily available for the general public. Open-access databases and their articles are also available online. Whereas this information tends to be more updated than books, there is much variability with online material in terms of when or how often information is published and distributed. Additionally, because it is very easy to publish information online, and subsequently information posted online does not always have a professional vetting process, information found online may be less trustworthy than other sources. Therefore, this requires the information seeker to be extra vigilant in using their information evaluation skills to determine the quality of the information found online. Generally, government information is solid, unless the government itself is known to be questionable. 

Professional Information in Prior and Current Research

Peer-reviewed journal articles have the most reputable information. They also contain the most recent findings and trends. However, they usually are written by professionals for professionals, and these have an extensive reviewing and vetting process to ensure that high-quality information is published. However, depending on what and why you are writing, and the level of information needed for your audience, a high level of knowledge and vetting may not be necessary (although it usually is in an academic context). Also, peer-reviewed journal articles are highly specific to a particular topic. If more general information is needed, unless it can be found in a literature review or meta-analysis, then other sources would more likely be needed. 

Continue here to learn about primary, secondary, and tertiary resources.