Many times I saw the phrase something 101, such as Microsoft Excel 101. What exactly does it mean?


It means "introductory something". The allusion is to a college course with the course code 101, which in the American system and probably others indicates an introductory course, often with no prerequisites.

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    It's primarily American usage. Room 101 means something entirely different. – RedGrittyBrick Feb 26 '11 at 18:12
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    @RedGrittyBrick: Mmm, yes. 101 for thoughtcrime. – chaos Feb 26 '11 at 18:19
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    Does it means the same as something ABC? – Yousui Feb 26 '11 at 18:26
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    @Yousui: Not entirely. The emphasis in something ABC is more on an implication that the material is going to be presented in a simple, step-by-step manner, and sometimes people put the label on rather advanced topics. (Admittedly, the same thing gets done with 101.) Usually a something ABC is going to be introductory, though. – chaos Feb 26 '11 at 18:31
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    @Yousui And while we're disambiguating, something A to Z means a complete or comprehensive introductory survey of a subject. So, for example, "Wine 101" = "Introduction to wine for the novice", "Wine ABC" = "Getting into wine, step by step", and "Wine A to Z" = "Everything you need to know about wine" – Jonathan Van Matre Dec 22 '11 at 16:43

It means:

  1. (chiefly US, postpositive) Basic, beginner, starting from scratch.

    Geology 101 tells us that you can't build a reservoir on sandstone.


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In universities courses are (usually) marked by numbers, since they are hard to remember by name. First number corresponds to study year this course should be taken in, followed by 2 (or 3) course id. Usually the same subject course has greater id if they have to be taken in the same year. Therefore lower ids are usually assigned to basic courses. So, most basic course would be 101 then as the first 1 is for the 1st year & 01 is first the 1st course.

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    This convention isn't always followed. At TAMU, the introductory physics courses are PHYS 218 and PHYS 208 -- in that order. – Dan Feb 27 '11 at 4:42

101 is the lowest course number, there's no 'zeroth' level. If someone attends a 220 course, they probably had 101 and 201 first.

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    Be aware that this usage is not uniform. At least some campuses of the University of California put lower division between 1 and 99, upper division from 100-199, and graduate course work from 200 up. – dmckee --- ex-moderator kitten Feb 26 '11 at 21:40
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    There are certainly 0-level courses. They don't usually count for much. I took Music 060 every semester for four years. It was the one-credit string orchestra for non-music-majors. – Rob Kennedy Feb 27 '11 at 7:17
  • Oh, okay. That makes a lot of sense for non-majors. – thyx Feb 27 '11 at 21:52

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