know something inside out
/ˌnəʊ ˌsʌm.θɪŋ ˌɪn.saɪd ˈaʊt/idiom
to know something extremely well
знать вдоль и поперёк
Русский аналог: «знать как свои пять пальцев»
В американском английском также know something inside and out. Не путать с inside out — «наизнанку»: He was wearing his jumper inside out.
“She knows the city inside out.”
“After twenty years, he knows the business inside out.”
“Ask Tom — he knows this software inside out.”