out of fashion or out of date

at the most modern stage of development in a particular type of work or activity

to prevent something happening smoothly in the way that it was planned, by causing a problem or difficulty.

to allow something new to start

to suddenly lose the energy or interest to continue doing what you are doing

the detailed or complicated facts of something

not difficult, easy to implement, easy to understand

If you talk about the nuts and bolts of a subject or an activity, you are referring to the detailed practical aspects of it rather than abstract ideas about it.

To revise something (such as a plan) from the beginning, typically after it has failed / start over

to misunderstand somebody; to become confused

to cleverly do or say exactly what is needed to achieve a desired result or elicit a specific reaction from someone or a situation

to examine something very carefully in order to improve it in the future

to waste time doing things that others have already done