Morphology is the study of the formation and inflection of words. It studies how morphemes (the smallest units of meaning) are combined to form words from components such as roots and affixes. For example, the word dogs contains two morphemes dog and the plural s.
Morpheme is the smallest meaningful unit of a language. A vocal-auditory morpheme is composed of phonemes, the smallest units of sound. A written morpheme is composed of graphemes, the smallest units of a written language (e.g. alphabetical letters). A visual-manual morpheme is composed of parameters (equivalent to phonemes).
A free morpheme is when it can stand alone as a word. E.g. dog, stop in English. There are many free morphemes in ASL, such as again, love, see, your, etc.
Bound morphemes are the meaningful units that cannot stand alone. They are the affixes attached to a word. E.g. dogs (two morphemes), unstoppable (three morphemes), abnormal (two morphemes) in English. Examples in ASL: teacher, three-month, four-week, etc. The numeral handshape is a "bound morpheme" that is affixed to a ASL word, such as day, week, month, year and some other words/signs. This process is known as called numeral incorporation .
Derivational morphemes - to create another meaning or word. E.g. nothingness, deafhood. ASL example: deafhood, sit/chair, again/often
Inflectional morpheme modifies a word's tense, aspect, etc. ASL examples: again-again-again, weekly, monthly
 Numeral incorporation are described in works by Scott Liddell and Robert E. Johnson.