The voiceless glottal transition, commonly called a "fricative", is a type of sound used in some spokenlanguages which often behaves like a consonant, but sometimes behaves more like a vowel, or is indeterminate in its behavior. The symbol in the International Phonetic Alphabet that represents this sound is , and the equivalent X-SAMPA symbol is h. People lacking this sound in their native language often have difficulty trying to produce it. Notably, speakers of French.
See more at Wikipedia.org...