  The dynamics of a barred galaxy depends on the pattern speed of its bar. The
only direct method for measuring the pattern speed of a bar is the
Tremaine-Weinberg technique. This method is best suited to the analysis of the
distribution and dynamics of the stellar component. Therefore it has been
mostly used for early-type barred galaxies. Most of them host a classical
bulge. On the other hand, a variety of indirect methods, which are based on the
analysis of the distribution and dynamics of the gaseous component, has been
used to measure the bar pattern speed in late-type barred galaxies. Nearly all
the measured bars are as rapidly rotating as they can be. By comparing this
result with high-resolution numerical simulations of bars in dark matter halos,
it is possible to conclude that these bars reside in maximal disks.
