  The rapid advances in infrared detector technology over the past decades have
impelled the development of wide-field instruments, and shaped our view of the
cold universe. Large scale surveys in our Galaxy have discovered hundreds of
brown dwarfs enabling the characterisation of the mass function in the
substellar regime. I will review the most recent observational results
concerning the substellar IMF derived in star forming regions, open clusters,
and the field, that must be reproduced and explained by any successful star
formation theory.
