  Results of the study of the symbiotic binary Z And during its recent active
phase 2000 -- 2010 when it experienced a series of six optical outbursts are
presented. High-resolution spectra obtained during the first and fourth
outburst, which was the strongest one, have been analyzed. These data are
compared with results of theoretical computations. The comparison provides
information about the behaviour of the system during the entire active phase
rather than during an individual outburst. In particular it was found
fundamental difference between the first outburst, which opened the active
phase, and the recurrent outbursts - namely, the presence of bipolar collimated
optical outflow during some of the recurrent outbursts. A scenario that can
explain all the spectroscopic phenomena observed during this active phase as
well as previous active phases of Z And is proposed. The possibility to use
this scenario for explanation of the line spectrum of other classical symbiotic
stars during their active phases is motivated.
