This one is much more a tech type thing so I'll move it in there. Short answer is braking - albeit lighter than your initial grab - all the way to the apex of the corner.
Here's a great overview from a respected source: Listen to Ken Hill Coaching #9 - Order of the Sport - Fundamentals - Brakes by Ken Hill Coaching #np on #SoundCloud https://soundcloud.com/ken-hill-534763963/ken-hill-coaching-9-order-of-the-sport-fundamentals-brakes Highly recommend his other podcasts as well.
u could write a short book on trail braking and the how and why of it. a more specific question would be better for an Internet forum. if I had to type something as short as possible... - trail braking is braking while turning. the word "trail" comes from the idea that one might want to trail off the brakes (reduce braking force) while adding lean angle. - why? racers do this because its faster. it can help the moto turn a tighter radius. it can increase front tire grip. it scrubs off speed and can allow u to brake later. all of those lead to lower lap times. - how? thats too much for 2 sentences. reducing brake pressure inversely proportional to added lean angle is a good start.
I really like understanding the science and math stuff behind things so maybe you do too. I guess the what it is is easy. Just breaking all the way to the apex (or about) while reducing pressure as you go. Ok so for the fun stuff. While the forks are compressed you get a much steeper angle on the steering which will make the bike far easy to turn. Secondly grip levels increase with more weight or forces being applied to the tires. Force = Mass x Acceleration but in this case I guess it's deacceleration. As you breaking your pushing that front tire into the ground which increases traction. If and when you start to practice trail braking DO NOT just let off them mid corner. I think most people learn trail braking though wreckless riding in a way. I know for myself I just entered corners way to fast and was like well ummmm here we go and then didn't crash. Some corners lend themselves to this a lot while others don't at all.
You trail brake in your car in every corner. Think about how you brake till you achieve the speed and direction you are happy with, then slowly applying less and less brake until you are back on the gas. That’s trail braking.