Limit[expr, x->$x_0$]Limit[expr, x->$x_0$, Direction->1]Limit[expr, x->$x_0$, Direction->-1]Limit[x, x->2]
Limit[Sin[x] / x, x->0]
The limit value can change depending on which direction the limit is approached from.
Consider this inverse x function:
Plot[1/x, {x, -10, +10}]
When coming to zero from positive values:
Limit[1/x, x->0, Direction->-1]
But when coming to zero from negative values:
Limit[1/x, x->0, Direction->1]
A limit can be Indeterminate:
Limit[Tan[x], x->Infinity]