The grammar of American Sign Language (ASL) has rules just like any other sign language or spoken language. ASL grammar studies date back to William Stokoe in the 1960s. This sign language consists of parameters that determine many other grammar rules. Typical word structure in ASL conforms to the SVO/OSV and topic-comment form, supplemented by a noun-adjective order and time-sequenced ordering of clauses. ASL has large CP and DP syntax systems, and also doesn't contain many conjunctions like some other languages do.
Morphology
ASL morphology consists of two different processes: derivational morphology and inflectional morphology.
Derivational morphology in ASL occurs when movement in a sign changes the meaning - often between a noun and a verb. For example, for the sign CHAIR, a noun, a person would tap their dominant pointer and middle fingers against their non-dominant pointer and middle fingers twice or more. For the sign SIT, a verb, a person would tap these fingers together only once and with more force.
Inflectional morphology adds units of language to other words. For example, this would be changing 'watch' to 'watches' or 'watching.' In ASL, the sign may remain unchanged as WATCH, or the meaning may change based on NMM (Non-Manual-Markers).
ASL morphology is demonstrated with reduplication and indexicality as well.
Derivation
Compounding is used to derive new words in ASL, which often differ in meaning from their constituent signs. For example, the signs FACE and STRONG compound to create a new sign FACE^STRONG, meaning 'to resemble'. Compounds undergo the phonetic process of "hold deletion", whereby the holds at the end of the first constituent and the beginning of the second are elided:
Many ASL nouns are derived from verbs. This may be done either by reduplicating the movement of the verb if the verb has a single movement, or by restraining (making smaller and faster) the movement of the verb if it already has repeated movement. For example, the noun CHAIR is derived from the verb SIT through reduplication. Another productive method is available for deriving nouns from non-stative verbs. This form of derivation modifies the verb's movement, reduplicating it in a "trilled" manner ("small, quick, stiff movements"). For example, this method is used to derive the noun ACTING from the verb ACT.
Characteristic adjectives, which refer to inherent states, may be derived from adjectives which refer to "incidental or temporary states". Characteristic adjectives always use both hands, even if the source adjective only uses one, and they always have repeated, circular movement. Additionally, if the source adjective was one-handed, the derived adjective has alternating movement. "Trilling" may also be used productively to derive adjectives with an "ish" meaning, e.g. BLUE becomes BLUISH.
ASL occasionally uses suffixation in derivation, but less often than in English. Agent nouns may be derived from verbs by adding the suffix AGENT and deleting the final hold of the verb, e.g. TEACH+AGENT 'teacher'. Superlatives are also formed by suffixation, e.g. SMART+MOST 'smartest'.
Certain types of signs, for example those relating to time and age, may incorporate numbers by assimilating their handshape. For example, the word WEEK has handshape /B/ with the weak hand and /1/ with the active hand; the active hand's handshape may be changed to the handshape of any number up to 9 to indicate that many weeks.
There are about 20 non-manual modifiers in ASL, which are either adjectival or adverbial. For example, the adverb 'th', realized as the tongue being placed between the teeth, means 'carelessly / lazily' when combined with a verb:
Degree
Mouthing is when an individual appears to be making speech sounds, and this is very important for fluent signing. It also has specific morphological uses. For example, one may sign 'man tall' to indicate the man is tall, but by mouthing the syllable cha while signing 'tall', the phrase becomes that man is enormous!