  In an effort to characterize variations on the time scale of hours and
smaller during the high and low states of the novalike variable TT Ari, light
curves taken over the course of more than 40 yr are analyzed. It is found that
the well known negative superhump observed during the high state persists until
the present day at an average period of 0.13295 d which is slightly variable
from year to year and exhibits substantial amplitude changes. The beat period
between superhump and orbital period is also seen. QPOs occur at a preferred
quasi-period of 18 -- 25 min and undergo a systematic frequency evolution
during a night. The available data permit for the first time a detailed
investigation of the low state which is highly structured on time-scales of
tens of days. On hourly time scales the light curve exhibits strong variations
which are mostly irregular. However, during an interval of several days at the
start of the low state, coherent 1.2 mag oscillations with a period of 8.90 h
are seen. During the deep low state quiet phases and strong (1.5 -- 3 mag),
highly structured flares alternate in irregular intervals of roughly 1 day. The
quiet phases are modulated on the orbital period of TT Ari, suggesting
reflection of the light of the primary component off the secondary. This is the
first time that the orbital period is seen in photometric data.
