An integral can be defined for all values (that is, for all $X$). An example of this type of function is the polynomial - which we will study in the coming years.

However**, there are integrals that are not defined for all values (all** **$X$****), since if we place certain** **$X$**** or a certain range of values of** **$X$**** we will receive an expression considered "invalid" in mathematics. The values of** **$X$**** for which integration is undefined cause the discontinuity of a function.**