Academic indexing databases can guide you to articles published in the scholarly journal literature. Some also include conference papers and other material. In many cases, these databases are subject-specific. For North American History, an excellent source would be “America History and Life”. For history of the world outside North America, “Historical Abstracts” would be preferred. Articles discussing environmental and pollution issues would be covered in databases such as “Environmental Sciences and Pollution Management”. Or they might be included in a biological one such as BIOSIS.
A term paper topic could require researching several different aspects of a subject before deciding which one to focus on in your paper. Or a topic assigned for a group project could require researching and incorporating several different aspects into the project report. Relevant information might be scattered through a number of databases. That in turn would require deciding which ones to use, then performing separate searches in each one. Their search pages do not all work exactly the same.
Google Scholar operates somewhat differently.