The vacuum energy: Casimir effect and the cosmological constant

This is a short summary of the talk given at the meeting, wich comprised considerations on the zero point energy and some aspects of the Casimir effect. In particular, recent developments on the construction by the author and J. Haro of the first consistent proof of the dynamical Casimir effect, on the possible contribution of vacuum fluctuations to the cosmological constant, and on some new theories about it, discuseed at the meeting, are also reported.