Escape of special characters such as question marks in Regular Expressions

Escape of special characters such as question marks in Regular Expressions

In the character escape section of the. NET Framework developer guide, there is such a paragraph.
Except. $ ^ {[(|) * +? \, Other characters match themselves.
But it does not indicate why these characters should match.
I wrote it here for convenience of future reference and searching by netizens.

[SIPO]
Escape of point:. ==>\\ u002e
Escape of dollar signs: $ ==>\\ u0024
Escape of the multiplication Symbol: ^ ==>\\ u005e
Escape from the left braces: {=>\\ u007b
Escape from left square brackets: [==>\\ u005b
Escape of left parentheses: (==>\\ u0028
Escape of vertical bars: |=>\\ u007c
Escape of right parentheses: ==>\\ u0029
Asterisk escape: * ==>\\ u002a
Escape of the plus sign: + ==>\\ u002b
Escape question mark :? ==>\\ U003f
Escape the backslash: \=>\\ u005c