What distinguishes statically typed languages from dynamically typed languages?

Statically typed languages require data types to be defined beforehand, meaning that each variable must be assigned a type at compile time. This characteristic allows for type checking to occur during the compilation process, which helps catch type-related errors before the program is executed.

By having a defined type for each variable, statically typed languages can leverage this information to optimize performance and memory management. This approach often results in more predictable behavior, as the types of variables are known ahead of time.

In contrast, dynamically typed languages determine variable types at runtime, allowing for more flexibility but also increasing the potential for runtime errors due to type mismatches. Thus, the defining feature of static typing is the necessity to declare types in advance, contrasting with the fluid nature of dynamic typing.