Summability refers to the property of a sequence or series that allows it to be assigned a meaningful sum, even if the traditional sum does not exist. This concept is particularly important in mathematics, especially in the study of infinite series. Various methods, such as Cesàro summation and Abel summation, are used to extend the idea of summation to include divergent series. In practical terms, summability helps mathematicians and scientists analyze and interpret data that may not converge in the usual sense. By applying summability techniques, one can extract useful information from sequences that would otherwise be considered undefined or meaningless. This has applications in areas like functional analysis and number theory.