Introduction
A literature review can be understood as its form of research, which is called secondary research and is sometimes referred to as library research. If you don’t do a literature review, in other words, if you don’t read any background information, then your only resource is your personal experience. It appears you are unaware of the published findings of others. It made sense to use the past tense in all sections because the research had already been accomplished.
The literature review is the star of the introduction. The most obvious feature of a literature review is the discussion and citation of relevant material, including journal articles, book, review, conference papers, and even personal communication, all of which taken together can be called the literature.