A scientific paper usually consists of 4 or more big sections: introduction, content, conclusions, and references.
The introduction initially states the problem and introduces relevant information to the reader. Usually, inside the introduction, the scientist summarizes the related work or state of the art. After the state of the art, the scientist gives a brief explanation of the technique he or she proposes and what is the contribution to science or the new discovery made. This brief explanation introduces the next section: the content.
The content of the paper can be divided into several sections or subsections, each of them addressing a part of the scientific discovery.
There is a common feature to all scientific papers ever published, they all have a contribution to science. It can be a great contribution like Einstein's equation $E=mc^2$  or a small one like Fierro's PhD thesis . However, all of them make a step further in the path of science.
The numbers inside the square brackets are called the references, which have a different section located always at the end of the document. References are very important in science since it helps us to cite other authors and relate our work to theirs.
The conclusions summarize the main aspects of the paper. Sometimes here can be included the future developments the researcher wants to perform. It may also include the acknowledgments. I would like to thank José Ignacio Fernández, CTO of Traity, this blog is based on his original idea .