The head forward posture that has come to be known as text neck is everywhere because people are constantly on their phones. This is a head forward posture that comes from looking down at the phone
Spending time in head forward posture will compress and tighten muscles, tendons, and ligaments at the front of the neck while tightening muscles, tendons, and ligaments on the back
For me, this means my trapezius (shoulder shrug) muscles get tight and sore: really unpleasant
What to do about text neck
The first obvious thing is to change the way you hold your phone. Hold it up to your face instead of the other way around. Taking breaks from your phone and doing some stretching will also help.
If you have trapezius pain as I did, doing some simple yoga poses a few times a day will result in significant pain relief. The most effective poses are chest openers. Here are a few for you to try:
Bridge: Lay on your back, feed hip-distance apart, hands to your sides. Lift your hips up off the mat. Do not crunch your neck by being too vigorous. This should be gentle. Feel the stretch across the chest. Hold 30 seconds or longer if it feels good to you.
Locust: Lay on your stomach. Gently lift your upper body and legs off the mat. Hold your hands up behind you. Do not crunch your lower back. Hold for 30 seconds or longer if it feels good to you.
Savasana or Corpse: Lay on your back, feet hip-distance apart, hands to your sides. You may want a rolled-up towel under your knees and a small pillow under your head. Maintain a neutral spine. Try to get your shoulders to the floor, but without straining. You can modify and get more chest opening by holding arms overhead (but still on the floor). Hold 30-seconds or longer if it feels good to you.