Most languages do some checks at runtime. This is the strong / weak typing dichotomy (which is different from the static/ dynamic one). For example, Java will

Most languages do some checks at runtime. This is the strong / weak typing dichotomy (which is different from the static/ dynamic one). For example, Java will throw an exception at runtime if an object is cast (using .asInstanceOf) to an incompatible class. Python throws if you add an integer to a string. Both of those languages are strongly typed. On the other hand, C has no runtime checks whatsoever. If you add a number to an array the program will happily move the array pointer and maybe overflow, but even that won't cause a runtime failure every time.