  Electromagnetic probes are excellent messengers from the hot and dense medium
created in high-energy heavy-ion collisions. Since leptons do not interact
strongly, their spectra reflect the entire space-time evolution of the
collision. The surrounding medium can lead to modifications of the dielectron
production with respect to the vacuum rate. To quantify modifications in
heavy-ion collisions, measurements in pp collisions serve as a reference, while
the analysis of p-A collisions allows for the disentanglement of cold nuclear
matter effects from those of the hot and dense medium. In this proceedings,
dielectron measurements with the ALICE central barrel detectors are presented.
The invariant mass distributions in the range $ 0<m_{ee}<3 $ GeV/$ c^{2} $ are
compared to the expected yields from hadronic sources for pp collisions at $
\sqrt{s}=7 $ TeV, and for p-Pb collisions at $ \sqrt{s_{\rm NN}}=5.02 $ TeV.
The cross section of direct photons measured via virtual photons in pp
collisions is compared to predictions from NLO pQCD calculations as a function
of the transverse momentum. The status of the analysis of Pb-Pb collisions at $
\sqrt{s_{\rm NN}}=2.76 $ TeV is presented.
