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Ne present the general properties o f jets produced by e+e' annihilation.Their production and fragmentation characteristics have been studied w i t h charged p a r t i c l e s for c.m. energies between 12 and 43 GeV. In this energy range e+e' annihilation into hadrons i s dominated by pair production o f the f i v e quarks u ‚ d , s ‚ c and b . In addition, hard gluon bremsstrahlung effects which are i n v i s i b l e a t low energies become prominent at the high energies.The observed multiplicity distributions deviate from a Poisson distribution. The m u l t i p l i c i t y distributions for the overall event as well as for each event hemisphere s a t i s f y KNO s c a l i n g to w i t h i n "20 %. The distributions o fxp = 2p/W are presented; scale breaking i s observed a t the l e v e l o f 25 %.The quantity xp dcr/dxp i s compared w i t h multigluon emission calculations which predict a Gaussian distribution i n terms o f ß n ( 1 / x ) . The observed energy dependence o f the maximum o f the distributions i s i n qualitative agreement with the calculations. P a r t i c l e production i s analysed w i t h respect to the jet a x i s and longitudinal and transverse momentum spectra are pre-' sented. The angular distribution o f the j e t a x i s strongly supports the idea o f predominant spin 1/2 quark p a i r production. The p a r t i c l e distributions w i t h respect t o the event plane show clearly the growing importance o f planar events with increasing c.m. energies. They a l s o exclude the presence of heavy quark production, e+e_ + 00, for quark masses up to _. 5 < mQ < 20.3 GeV ([eQI = 2/3) and.J < mQ < 19 GeV ( l t = 1/3). The comparison o f 1/otot do/d measured a t 14, 22 and 34 GeV suggests that hard gluon bremsstrahlung contributes mainly to transverse momenta larger than 0 . 5 GeV/c. The rapidity distribution for w 3 22 GeV shows an enhancement away from y = 0 which corresponds to an increase i n y i e l d o f 10 -15 % compared to the centre region ( y = 0 ) . The enhancement probably results from heavy quark production and gluon bremsstrahlung. The p a r t i c l e f l u x around the jet axis shows w i t h increasing c.m. energy a rapidly growing number o f particles collimated around the j e t a x i s , w h i l e a t large angles t o the j e t a x i s almost no W dependence i s _ o b s e r v e d . For f i x e d longitudinal momentum p|| approximate " f a n invariance" i s seen: The shape of the angular distribution around the jet a x i s i s almost independent o f w. The collimation depends strongly on p". For small p"‚ p" < 0 . 2 GeV/c, isotropy i s observed.With increasing p" the particles tend to be emitted closer and c l o s e r t o the jet a x i s .

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