  About one thousand extragalactic large-scale jets are known, and a few tens
of them are confirmed sources of infrared, optical, or X-ray photons.
Multiwavelength emission comming directly from these outflows is always
non-thermal in origin. This fact constitutes a primary difficulty in extracting
unknown parameters of large-scale jets, since the non-thermal featureless
continua do not allow to infer undoubtfully (or even at all) bulk velocities
and composition of the radiating plasma. In addition, arcsecond spatial
resolution, limited sensitivity and narrow energy bands of the best
high-frequency telescopes like Spitzer, Hubble and Chandra, preclude precise
constraints on the spectral and morphological properties of the discussed
objects. Nevertheless, new multiwavelength observations have substantially
enriched our knowledge on extragalactic large-scale jets, in many aspects,
however, by means of challenging previous predictions and expectations. In this
short contribution I will concentrate on the following issue: what can be
learned by analyzing broad-band emission of the discussed objects about
particle acceleration processes acting thereby and about jet internal
parameters.
