Stop sounds can be voiceless, like the sounds /p/, /t/, and /k/, or voiced, like /b/, /d/, and /g/. In phonetics, a plosive consonant is made by blocking a part of the mouth so that no air can pass through. Pressure builds up behind the block, and when the air is allowed to pass through again, a sound is created. This sound is the plosive consonant. The blocking is usually done using the tongue, the lips or the throat. Plosives can be voiced or voiceless.
[p], [t], [k] are voiceless plosives.
[b], [d], [ɡ] are voiced plosives.
[ʔ] is a glottal stop which is made in the throat. There are six stop consonants in American English: T, D, B, P, G, and K.