the nuts and bolts
The most basic, fundamental, or essential aspects of something. Japanese is intimidating because of the written characters, but the nuts and bolts of the language are actually pretty straightforward. We came up with a lot of big ideas, but no one addressed the nuts and bolts of how to implement them.
the nuts and bolts of something
COMMON The nuts and bolts of something are the detailed, practical facts about it, and not just ideas or thoughts about it. Tonight, the prize-winning author will discuss the nuts and bolts of the writer's craft. Note: You can also use nuts-and-bolts before a noun. It is very much a nuts-and-bolts guide for the serious gardener. I'm a nuts-and-bolts politician. I always have been.