the nuts and bolts
idiom

- the practical facts about a particular thing, rather than theoretical ideas about it

nuts-and-bolts
-adjective

- practical

(Cambridge Advanced Learner's Dictionary)

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Fasteners such as nuts, bolts and screws have been around for centuries. The Romans used nuts and bolts to secure chariot wheels but it was the great Leonardo da Vinci in the late 1400's who first demonstrated the use of a jack screw for lifting loads.

When used in a figurative sense, nuts and bolts is a so-called Siamese twin phrase, in which two related words are used to describe something or to express a concept. This saying stems from the use of real nuts and bolts to fasten primarily metal objects together, such as machinery parts.

Because they serve as the foundation or basis for a system, nuts and bolts are a vital and practical element, as opposed to the outer appearance or a function that is merely "nice to have." So in a figurative sense nuts and bolts denotes the practical aspect of something.

Following are examples of other common Siamese twin expressions:

- dog and pony show = a display, demonstration or exhibition of something, such as something one is selling (That was quite the dog and pony show that you put on in front of the customer)

- song and dance = an excessively elaborate effort, explanation or justification, often misleading or evasive (He did a song and dance when the train personnel asked to see his ticket)

- cat and mouse = to try to defeat someone by tricking them into making a mistake so that you have an advantage over them (The thief played cat and mouse with the police for months before being captured)

- apples and oranges = to explain why two things cannot be compared (Of course the flat screen TV has a better picture than an old cathode ray tube model. That's apples and oranges!)

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SYNONYMS

basics, brass tacks, essentials, fundamentals, inner workings, nitty-gritty, no frills, no nonsense, practical details

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Practice OWAD in a conversation today, say something like:

"When using new software, learn THE NUTS AND BOLTS first before trying out advanced features."