  Various scenarios of contact binary evolution have been proposed in the past,
giving hints of (sometimes contradictory) evolutionary sequence connecting
A-type and W-type systems. As the components of close detached binaries
approach each other and contact binaries are formed, following evolutionary
paths transform them into systems of two categories: A-type and W-type. The
systems evolve in a similar way but under slightly different circumstances. The
mass/energy transfer rate is different, leading to quite different evolutionary
results. An alternative scenario of evolution in contact is presented and
discussed, based on the observational data of over a hundred low-temperature
contact binaries. It results from the observed correlations among contact
binary physical and orbital parameters. Theoretical tracks are computed
assuming angular momentum loss from a system via stellar wind, accompanied by
mass transfer from an advanced evolutionary secondary to the main sequence
primary. Good agreement is seen between the tracks and the observed graphs.
Independently of details of the evolution in contact and a relation between
A-type and W-type systems, the ultimate fate of contact binaries involves the
coalescence of both components into a single fast rotating star.
