在计算机科学中，一部分编程语言具备型别安全的性质。这个术语在不同的社区中有不同的定义，特别是正规的型别理论上的定义远远强过大多数的程序员的理解，但对于使用型别系统的认知，皆旨在避免必然的错误形式，和不良的程序行为（称为型别错误）。

类型错误（type error）是错误或不期望的进程行为，由不同数据类型的差别所引起，适用于进程的常量、变量、方法（函数），如把整型（int）当作了浮点型（float）。

中国大陆用语习惯称型别为类型；称数据为数据。

型别安全可以静态方式实施，及早在编译时期就捕捉到潜藏的错误；或者以动态方式，在运行时期关联型别的信息，并在必要时检测即将发生的错误。型别安全是编程语言的性质，而不是程序所自有的。例如，有可能以型别不安全的语言，编写出型别安全的程序。在此是以编程语言为主，而不讨论以个人能力维护的型别安全。

In computer science, type safety is the extent to which a programming language discourages or prevents type errors. A type error is erroneous or undesirable program behaviour caused by a discrepancy between differing data types for the program's constants, variables, and methods (functions), e.g., treating an integer (int) as a floating-point number (float). Type safety is sometimes alternatively considered to be a property of a computer program rather than the language in which that program is written; that is, some languages have type-safe facilities that can be circumvented by programmers who adopt practices that exhibit poor type safety. The formal type-theoretic definition of type safety is considerably stronger than what is understood by most programmers.