  The combined vertexing and tracking performance of the innermost part of the
FCC-ee experiments must deliver outstanding precision for measurement of the
track momentum together with an impact parameter resolution exceeding by at
least a factor five that typically achieved at LHC experiments. Furthermore,
precision measurements require stability and fiducial accuracy at a level which
is unprecedented in collider experiments. For the innermost vertex layers these
goals translate into a target hit resolution of approximately 3 $\mu$m together
with a material budget of around 0.2\% of a radiation length per layer.
Typically this performance might be provided by silicon-based tracking,
together with a careful choice of a low-mass cooling technology, and a stable,
low mass mechanical structure capable of providing measurements with a low
enough systematic error to match the tremendous statistics expected,
particularly for the run around the Z resonance. At FCC-ee, the magnetic field
will be limited to approximately 2\,T, in order to contain the vertical
emittance at the Z pole, and a tracking volume up to relative large radius is
needed. The technological solution could be silicon or gaseous based tracking,
in both cases with the focus on optimising the material budget, and particle
identification capability would be an advantage. Depending on the global
design, an additional silicon tracking layer could be added at the outer radius
of the tracker to provide a final precise point contributing to the momentum or
possibly time of flight measurement. Current developments in monolithic and
hybrid silicon technology, as well as advanced gaseous tracking developments
provide an encouraging road map towards the FCC-ee detector. The current state
of the art and potential extensions will be discussed.
