  We present a study of high-resolution spectra of RS Canum Venaticorum (RS
CVn), a prototype of active binary systems. Our data were obtained from 1998 to
2017 using different telescopes. We analyze the chromospheric activity
indicators Ca II IRT, H$_{\alpha}$, Na I D$_{1}$, D$_{2}$ doublet, He I
D$_{3}$, and H$_{\beta}$ using a spectral subtraction technique. The
chromospheric emission stems mainly from the K2 IV primary star, while the F5 V
secondary star only shows weak emission features in a few of our spectra. We
find excess absorption features in the subtracted H$_{\alpha}$ lines and other
activity indicators from spectra taken near primary eclipse, which we ascribe
to prominence-like material associated with the primary star. We estimate size
limits of these tentative prominences based on the geometry of the binary
system, and investigate the physical properties of the strongest prominence. An
optical flare, characterized by He I D$_{3}$ line emission, together with
stronger emission in other activity lines, was detected. The flare energy is
roughly comparable to strong flares observed on other RS CVn-type stars. The
chromospherically active longitudes of RS CVn most frequently appear near the
two quadratures of the system and display changes between observing runs, which
indicates an ongoing evolution of its active regions.
