I don't know your experience so I'll explain briefly.
KIAS comes from the speed of the air going into the pitot tube and shows on
your air speed indicator. Most show KIAS and not KTAS (knots true airspeed)
but have a calibration knob to make corrections. KIAS is the speed the
airplane "thinks" it is moving through the air. Hence, flying into a head
wind, KIAS will be higher than actual speed and a flying with a tailwind
would show lower than actual speed. KTAS is obtained by math. Remember,
they told us "some day you'll need this". It's obtained with altitude and
temperature.


Actually KIAS is measured by comparing the air pressure inside the pitot tube
and comparing it to the pressure of non moving air outside the pitot tube.
Strictly speaking TAS needs barometric pressure as well in the calculation.
Aerial navigators used to navigate by pressure patterns comparing TAS vatiation
over a period of time to known meteorological conditons. Not an exact science
but good for another data point. The comment about KIAS and headwind/tailwind
applies to groundspeed not TAS. The relationship between IAS and TAS is the
same no matter the winds.