Introduction

Until now, much of your science writing has focused on writing reports in which you simply described what you did and what you found. Although this will help you write the central ‘report’ sections (Methodology and Results) of a research paper or thesis, it doesn’t prepare you for writing an Introduction to a full-length research article; this is a new task that faces you once you move on to research writing.

In practice, you will find that you need to be certain about what you have done and what you have found in order to write the Introduction, and so the best time to write it will be after you have written, or at least drafted, the report sections. However, in this book, the structure of a research article is presented in the order in which it appears in a paper/thesis so that you can trace the connections between each part and see the sequence in which information is presented to the reader.

You may want to start your Introduction by describing the problem you are trying to solve, or the aim of your work, but as you will see when you examine published work, this is not how most research papers begin — and therefore it is not the best way for you to begin. In order to help you write the Introduction to your own research, the model you build must answer the following three questions:

• How do writers normally start the Introduction?
• What type of information should be in my Introduction, and in what order?
• How do writers normally end the Introduction?

Source: http://www.ehu.eus/ccwintco/uploads/e/ef/How_to_write_a_good_introduction.pdf
Additional information: https://explorable.com/how-to-write-an-introduction