Contrary to popular belief, there is no one singular universal sign language.  Signs vary from continents to
  countries and even in regions where one encounters different dialects
  The main "English" languages are the BSL (British Sign Language), ASL (American Sign Language) and
  SASL (South African Sign Language).  The differences are nominal and even a German and Englishman
  can understand one another and sign a conversation within half an hour of each other's company
  Currently there are efforts underway to establish a complete universal sign language, but the completion
  and implementation is still far from finalised
  Sign Language is not the letters of the alphabet.  Sign Language is a Deaf Language that uses gestures
  that has developed and is conveyed through four basic interactions :
    hand form (sign) formation i.e. position of fingers / palm / hand posture etc.
    use of facial expression
    use of upper torso positioning
    use of movement of the hand / wrist / arm etc.
  So, what it the ABC all about then?
  That is Finger Spelling and is used where Deaf persons have been exposed to some written language
  before (English / Afrikaans / Zulu etc.) and there is a need to "spell out" a name (e.g. John, Suzan) or a
  place (e.g. Durban, Victoria Street) and for concepts where one may not have a sign for or have forgotten it
  Any hand form has four elements that defines its meaning :
    hand formation - the different shapes that hand can be used in
    location - where the hand is placed in relation to the rest of the body
    motion - e.g. the index finger may be used to indicate a "z" or used in a circle
    orientation - mostly referring to the palm, i.e. facing up / down / forward etc.
  Facial expressions are vitally important, as they express the grammar and emotion of the conversation
  For example - there are distinct differences between YES / NO questions and WHO / WHAT / WHERE
  type questions - even in spoken languages.  Using a certain gesture with different facial movements can
  have varying and sometimes quite opposing meanings
  Upper torso positioning emphasises emotion in the conversation and is used to express the mood of the
  sign in relation to other signs e.g. shoulders back / slumped, chest out, leaning forward / sideways etc.
  Hand movement can completely alter the meaning of a hand form, e.g. forward motion is different from a
  sideways or rocking or chopping or rubbing or circular motion
  Certain hand forms may have different meanings to different groups, i.e. cultures / religions / ethnicity etc.
  and from one group to the next could have offensive or unacceptable outcomes which may be quite
  Some hand forms-movement-facial expression combinations in two languages may be exactly the same
  but could have different meanings
  Sign Language is therefore regarded as a true "living language" that evolves and develops every time there
  is a need for change or new additions to the language.  Because of its diversity along various groups,
  SASL (South African Sign Language) has been developed and has been included in the Constitution as the
  official instruction medium for the education of Deaf learners