What is Euler's buckling formula and what are its limitations?

Euler's formula for critical buckling load is Pcr = π²EI/(Le)², where Le is effective length depending on end conditions. Limitations include: applies only to long slender columns (slenderness ratio > 80-100), assumes elastic behavior, perfect geometry, and axial loading. For short columns, Johnson's parabolic formula or Rankine's formula is used as actual failure involves yielding.