  We review some recent results on D-branes on Calabi-Yau (CY) manifolds. We
show the existence of structures (helices and quivers) which enable one to make
statements about large families of D-branes in various phases of the Gauged
Linear Sigma Model (GLSM) associated with the CY manifold. A comparison of the
quivers of two phases leads to the prediction that certain D-brane
configurations will decay as one moves across phases. We discuss how boundary
fermions can be used to realise various D-brane configurations associated with
coherent sheaves in the GLSM with boundary.
  This is based on the talk presented by S.G. at Strings 2001, Mumbai.
