SPRING AND NEAP TIDES
the Earth–moon–sun geometry that makes the tides swing — after NOAA
CPR AND CHOKING
the 2025 American Heart Association algorithms, step by step — bystander, trained rescuer, and choking at three ages
THREE HAND STITCHES
backstitch · running stitch · whipstitch — what shows on the face and what the thread does underneath
HANDWASHING
five steps, and the 20 seconds that actually matter
STAIN REMOVAL
five stain classes and the method for each — per publication H.E. 2-840 of the University of Kentucky Cooperative Extension
BINARY COUNTING
five doubling cards build every number from 0 to 31 — exactly the way every computer counts
THE EXIT STATUS
One byte from a command to the shell: what the standard assigns in it, what it leaves to the system — and why “128 + signal number” is nowhere in the standard
FILE DESCRIPTORS
Three levels between a number and a file: what two numbers of one description share, what two descriptions do not — and where the offset lives
FILE LOCKS
A lock lies on a range of bytes, it has two different kinds of owner, and it guards no byte at all
FILE PERMISSIONS
Nine bits in three triads, three special bits — and why r and x on a directory are different powers
CSS FLEXBOX
main axis and cross axis · which property belongs to which
GIT WORKING AREAS
four areas · the command that moves code between them