  This paper reviews methods which can be used to detect binaries involving
low- and intermediate-mass stars, with special emphasis on evolved systems.
Besides the traditional methods involving radial-velocity or photometric
monitoring, the paper discusses as well less known methods involving astrometry
or maser (non-)detection. An extensive list of internet resources (mostly
catalogues/databases of orbits and individual measurements) for the study of
binary stars is provided at the end of the paper.
