The articulators are the parts of the vocal tract used to make speech sounds - in English, the tongue, lips, teeth, alveolar ridge, hard palate, velum and glottis.
When giving a voice-place-manner description of consonants, the articulators used to produce the sound are indicated under place - so eg :/m/ /w/ /p/ and /b/ are bilabial sounds (using both lips), /f/ and /v/ are labiodental sounds (using the top teeth and bottom lip).
In order to make other sounds the tongue is always involved, and it is therefore "assumed" in the place label rather than stated explicitly. For example: /t/ /d/ /s/ /z/ /l/ and /n/ are all alveolar sounds - meaning that the tongue touches the alveolar ridge as they are made; /ʃ/ /ʒ/ are palatal - the middle of the tongue touches the hard palate.
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