Summary of $pi$--$pi$ Scattering Experiments

Present status of the study of the low energy $pipi$ interaction is reviewed, including the recent results on reactions $pi N topipi N$ near threshold. Current experimental values of s-wave $pipi$ scattering lengths are compared with predictions of various theoretical models. Required experimental and theoretical improvements are discussed, in particular the need for a new $K_{e4}$ decay measurement, and a more reliable theoretical interpretation of the near-threshold $pi N topipi N$ data.