The topic of plasma flows and their influence on the equilibrium and s
tability properties of tokamak discharges is briefly reviewed. The sta
bility of high-n ballooning modes in the presence of sheared toroidal
rotation is discussed to highlight recent advances in our understandin
g of the spatial structure and temporal evolution of these modes. The
eikonal solution, which is mathematically equivalent to the normal mod
e solutions at the lowest order in 1/n, may not be physically relevant
for a variety of reasons. An analytic formulation of the normal mode
problem for high-n ballooning modes in the presence of sheared toroida
l flow in the high-beta large-aspect-ratio limit is presented. in cont
rast to earlier studies, the present formulation allows for large plas
ma shifts as well as accounting for changes in the shape of flux surfa
ces due to rotation effects.