The order book, the spread, depth, funding rates and what moves a price when nothing has happened. Written for people who already trade.
Nothing matches that. Try a shorter word.
It is the line traders notice last and complain about most. It is not a fee, it is not charged by the venue, and on a position held for weeks it can cost more than every trading fee you paid to open and close it.
A book is the most honest object on an exchange: every line is an order somebody has actually committed to. It is also the most over-interpreted, because a commitment can be withdrawn in a millisecond and most of them are.