The letter h represents the only glottal consonant existent, which is the voiceless glottal fricative.
The sound of h is:
h: hat, hate, hot.
To pronounce the letter h is necessary to know that the glottis is in the middle part of the larynx, the same place where the vocal cords are located. In fact, the pronunciation of h uses the glottis as primary articulation, that is why letter h is called glottal. The air is aspirated, that is, the air comes out of your mouth as you say the sound.
- h is voiceless, so the vocal cords do not vibrate during the articulation of the consonant
External link to Letter: H exercises (1162).