Type
Type 形態 / 形式 / 模樣 / 形狀
我認為 type 翻譯成「形態」/「型態」比較合適，甚至叫「形狀」或「模樣」都很好。因為一個 type 確實表現的是一段代碼的構成樣式、形狀、構造，如果這種樣式經常被看到，就可以抽象出來，並起一個名字，也就是稱之為「某型代碼」或「某種形態代碼」。這跟虎形、鶴形；可愛型、性感型，其實是一個道理。
形，外形、姿態、容貌、樣式等意，例如：形勢、形色、形式等。型，器物的模樣，引申為某種標準，型式、典範、態度、風格之意。例如：模型、典型。二字意思相近，有字典謂兩字相通。所以，凡與外貌有關的，用「形」字；凡人工鑄造出來的，或引申事物表現的格調，用「型」字。
英文的「形」為shape；英文的「型」為type、style。
In any programming language there are two main categories of types: primitive and composite.
Primitive types are atomic, i.e., they are not formed by the combination of other types. 基本的型態
Composite types are made of other types, either primitive or composite. 複合的型態
A data type is the type of data (value) a variable or constant can store in it.
Most programming languages deal with typed values, i.e., integers, booleans, vehicles, etc.
There are however, programming languages that have no types at all.
BCPL has only one data type, a word. Different operations treat each word as a different type.
A type is, in essence, a set of values. Some of these sets have a finite number of elements, while others are infinite.
For instance, the boolean data type is a set with two elements: true and false; however, the string data type is a set with an infinite number of elements.
Not every operation can be applied on every data type.
Types exist so that developers can represent entities from the real world in their programs. However, types are not the entities that they represent.
Types prevent the program from entering into undefined states.
Types are a form of documentation that the compiler can check.
Types classify programming languages along three most important dimensions: Statically vs Dynamically typed; Strongly vs Weakly typed; Structurally vs Nominally typed.
Value Types
A value type is a type whose value is copied when it’s assigned to a variable or constant, or when it’s passed to a function.
Reference Types
Unlike value types, reference types are not copied when they are assigned to a variable or constant, or when they are passed to a function. Rather than a copy, a reference to the same existing instance is used.
Classes are reference types.
Size of a Data Type ( a data's type / a value's type :-))
The size of a data type specifies the size of data that can be stored in a given variable or constant.
A Type’s size is measured in terms of bit and can store values up to 2 bits.
For a n bit system, it can store a maximum of 2n values in it.
Think of bit as a value that is either 0 or 1.
Ruby's Approach to Types
Ruby is a dynamically typed language, meaning that it does not require or enforce type annotations in its syntax. Variables in Ruby can hold references to objects of any type, and the type of a variable can change over its lifetime. This provides a great deal of flexibility and is a hallmark of Ruby's design philosophy, focusing on simplicity and productivity.
Ruby does not have syntax for types.
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