Embouchure

Embouchure - The way in which a player applies the mouth to the mouthpiece of a brass or wind instrument.

This term applies to the formation of the lips covered by the mouthpiece, the vibration necessary to produce the tone, and the training of the muscles of the face used in contracting the lips for a high note, and relaxing them for a low note.

Tongue Controlled Embouchure (TCE)

Understanding how to control your sound by
using the "tongue to bottom lip anchor"
There are many slight variations on the TCE method. My personal method is fairly simple:
"anchor the tongue to the bottom lip" and in my case, the tongue is always touching my bottom lip.
The method I used is based on the simple trick Herbert Clarke describes in his letter written below:
Some other players vary this TCE method slightly, and others use an entirely different method, and to each his own.

Herbert Clarke

Herbert Lincoln Clarke (September 12, 1867 – January 30, 1945) was an American cornetist, feature soloist, bandmaster, and composer. He is considered the most prominent cornetist of his time.

Clarke’s legacy includes composing a portion of the standard repertoire for the instrument, many recordings, as well as a seminal school of playing which emphasized not only technical aptitude, but also increased warmth and lyricism of tone. He also produced several method books that are still used by brass students, for example the Clarke Studies.