The period is called an "end stop" because it is used at the end of a sentence. More exactly, it closes declarative sentences—those which state a fact, perception, idea, belief, feeling—and it may also close an imperative sentence, or command (though these are often punctuated with an exclamation point).
The period is used after many abbreviations: Mr., Mrs., Ms., Dr. When such an abbreviation occurs at the end of a sentence, the period does double duty, closing the sentence as well as marking the abbreviation.
Some abbreviations do not take periods: government agencies, for instance, such as the SEC (Securities and Exchange Commission) or the GPO (Government Printing Office). If you are uncertain about whether a particular abbreviation requires a period, consult a dictionary or an appropriate manual of style.
Not all abbreviations, incidentally, are allowable in composition. Some are perfectly acceptable: SEC, GPO, or Mr.,
Mrs., Ms., Dr. (Most professors, though, do not like Prof.) Others are not universally accepted. For example, many teachers prefer that instead of &, i.e., etc., and e.g., you write out and, that is, and so on, for example. Colloquial, slangy abbreviations are not acceptable at all: econ and polysci are legitimate enough in conversation, but you should use the full words in composition.
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What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.