To gain an overview of content and vocabulary, especially when searching a new topic, consider searching...
Example of narrowing a broad topic:
Follow this link to a website that talks about narrowing a topic.
Example of broadening a narrow topic:
Sometimes in research one can have a very specific topic such as Food Banks in Nampa, Idaho. Being so specific may provide practical relevance but you might not encounter research articles specific to Nampa, Idaho. The idea is to take the central topic and apply it to the area of interest. Broadening your search strategy to such things as: Food Programs, Hunger, or Nutrition can often lead to relevant results. If you are interested in a specific geographic location expand your search to include: Idaho, Northwest, West, or United States. As a researcher you will need to compare and contrast the similarities and differences you in relation to your specific area of interest. Follow this link to a website which talks about broadening a topic in a bit more detail.
Remember, refining your research topic or question is an ongoing process. As you conduct your literature review, you may find that you need to narrow or broaden your topic. Don't be afraid to ask for help!