0x27 · 0100111

ASCII 39 — the ' character

Punctuation

' is 39 in decimal, 27 in hex and 0100111 in binary.

The marks scattered between the digits and the letters.

Seven bits

ASCII is seven bits wide, which is why there are 128 of them. The eighth bit was long left for parity.

0100111

One bit — the sixth, worth 32 — separates the cases. Off gives a capital, on gives a lowercase letter.

Kind: Punctuation
Decimal: 39
Hexadecimal: 0x27
Octal: 047
Binary: 0100111
HTML entity: '
Named entity: '
URL encoding: '
CSS escape: \27
Short escape: \'

Only \e is missing from standard C; GCC, shells and regex engines take it.

The chart

Eight columns for the top three bits, sixteen rows for the bottom four. The capitals column sits right beside the lowercase one — that is the shape of the table.

Codes either side

36 · $37 · %38 · &40 · (41 · )42 · *

How to read this

Add 32 to a capital and you get the lowercase letter — one bit flips.
Digits start at 48, so subtracting 48 from the code gives the number.
Holding Ctrl clears the top three bits — that is why Ctrl+I is a tab.
Everything under 32, plus 127, draws nothing. Those show their abbreviation instead.

Frequently asked questions

Q. What is the ASCII code for '?

Decimal 39, hex 27, octal 047, binary 0100111.

Q. How do I write ' in HTML?

As ', or by name as '.

Q. How does it go in a URL?

It can stay as it is — this character needs no encoding.

Q. Does ' have a partner?

No case partner: it is not a letter but a symbol.