They may be as basic as pictures on a board that are used to request food, drink, or other care; or they can be advanced speech generating devices, based on speech synthesis, that are capable of storing hundreds of phrases and words.
ðeɪ mˈeɪ biː æz bˈeɪsɪk æz pˈɪktʃɚz ˌɔn ɐ bˈoːɹd ðæt ɑːɹ jˈuːzd tə ɹᵻkwˈɛst fˈuːd, dɹˈɪŋk, ɔːɹ ˈʌðɚ kˈɛɹ; ɔːɹ ðeɪ kæn biː ɐdvˈænst spˈiːtʃ dʒˈɛnɚɹˌeɪɾɪŋ dɪvˈaɪsᵻz, bˈeɪst ˌɔn spˈiːtʃ sˈɪnθəsˌɪs, ðæt ɑːɹ kˈeɪpəbəl ʌv stˈoːɹɪŋ hˈʌndɹɪdz ʌv fɹˈeɪzᵻz ænd wˈɜːdz.