The second way one uses the word "thesis" is in reference to a major paper that one writes as a capstone for his or her bachelor's or master's degree. Whereas term papers are projects that last one term, theses are projects that last several terms. Theses are usually much, much longer than term papers, often stretching past two hundred pages. Perhaps counterintuitively, however, theses often cover much more specialized topics than term papers. For example, one may write a term paper on Herman Melville for a literature survey course, but one would be much more likely to write a thesis on homosexual symbolism in Herman Melville's Moby Dick or on some other extremely specific aspect of one of Melville's novels. In fact, one could write an entire thesis on a single paragraph of Moby Dick . The goal of a thesis is to expound fully one's opinion on a given subject and to confront and exhaust all the opposition to that opinion. Therefore, one usually specializes his or her thesis topic almost to the point of absurdity.
I actually wrote my introduction first because I know that I am not good with writing. So, doing it first gives me the chance to keep on improving it until it is good. Yes, you are right that, some times, we do not know the whole picture yet.. so as I went along, I changed it here and there a number of times, until everything is clear. Not only it was a good practice for me, it is also an exercise in understanding the sequence of my experiments and the overall findings. Yes, it is true that doing it last will make it a bit of a rush. I agree.
13. Include a title on your proposal. I'm amazed at how often the title is left for the end of the student's writing and then somehow forgotten when the proposal is prepared for the committee. A good proposal has a good title and it is the first thing to help the reader begin to understand the nature of your work. Use it wisely! Work on your title early in the process and revisit it often. It's easy for a reader to identify those proposals where the title has been focused upon by the student. Preparing a good title means: