Validator - what is it? Why is a micro-marking validator necessary?

Let's talk about code verification tools. A special tool that is created for this purpose is called a format validator. HTML will be used as an example. The validator for this markup language is quite suitable in order to explain the principle and give an example.

Why is it needed?

, , , . , , HTML-. , , , ( , ).

, , <!DOCTYPE>. , , . , HTML5. , . , HTML, CSS. . , , .

DOCTYPE

:

1. .
2. .
3. .
4. .

, DOCTYPE . , , , -. . , , .

. ? . , , – . , , . , -.

, HTML- – , , . RSS- CSS? , . : . – . , , .

-

, -. ? (RSS-, CSS HTML). . HTML . -, , . , . , , .

?

:

1. .
2. . , . - – .
3. Document Type Definition. , (, ) , , .
4. . , , Document Type Definition.

, – . , . ? , . , ( , ).

, – . , , -, . , – . ?

, . , , , . , .

, , . . , , .

,

? , , . , , , – . , . , , .

, . , Doctype, . , , . , . : . ARIA. , , . : ? , . – . ARIA .

, , . , .