Introductions

Generic Structure of an Introduction Section

General context of the work A bit more detail on the first few sentences in the Abstract. By all means: NEVER COPY-PASTE SENTENCES VERBATIM FROM THE ABSTRACT. You will make the reader annoyed.
Motivation Why did you do this work? An expansion of the 1-2 motivational sentences in the Abstract.
Key related work - the main work that gives your work context Keep references to a minimum; they should be handled in the Related Work section.
Structure of the paper The last paragraph may start with “The structure of this paper is as follows:”.
Example (short) Introduction - fairly good example. Clear and concise. Goldman, C. V. & J. S. Rosenschein (1994). Emergent Coordination Through the Use of Cooperative State-Changing Rules. Proceedings of the Twelfth International Workshop on Distributed Artificial Intelligence, 171-185.
Example (long) Introduction - actually a bit too long, and presents too much new content Enrico Giunchiglia, G. Neelakantan Kartha, Vladimir Lifschitz (1997). Representing Action: Indeterminacy and Ramifications. Artificial Intelligence, 95(2):409-438.
A better Introduction following a more stylized format Jürgen Schmidhuber & Rudolf Huber Learning to Generate Artificial Fovea Trajectories for Target Detection