Unicode Character codes:

Character codes for numbers, characters, text delimiters, accents, punctuation, and greek.

Numbers

Character	ASCII	ISO/IEC 8859-1	Unicode	HTML
0	48	048	U+0030	0
1	49	049	U+0031	1
2	50	050	U+0032	2
3	51	051	U+0033	3
4	52	052	U+0034	4
5	53	053	U+0035	5
6	54	054	U+0036	6
7	55	055	U+0037	7
8	56	056	U+0038	8
9	57	057	U+0039	9
¼		0188	U+00BC	¼
½		0189	U+00BD	½
¾		0190	U+00BE	¾
¹		0185	U+00B9	&sup1
²		0178	U+00B2	²
³		0179	U+00B3	³
:	58	058	U+003A	:
;	59	059	U+003B	;
<	60	060	U+003C	<
=	61	061	U+003D	=
>	62	062	U+003E	>
?	63	063	U+003F	?
@	64	064	U+0040	@

Characters A - Z, a-z

Character	ASCII	ISO/IEC 8859-1	Unicode	HTML	Character	ASCII	ISO/IEC 8859-1	Unicode	HTML
A	65	065	U+0041	A	a	97	097	U+0061	a
B	66	066	U+0042	B	b	98	098	U+0062	b
C	67	067	U+0043	C	c	99	099	U+0063	c
D	68	068	U+0044	D	d	100	0100	U+0064	d
E	69	069	U+0045	E	e	101	0101	U+0065	e
F	70	070	U+0046	F	f	102	0102	U+0066	f
G	71	071	U+0047	G	g	103	0103	U+0067	g
H	72	072	U+0048	H	h	104	0104	U+0068	h
I	73	073	U+0049	I	i	105	0105	U+0069	i
J	74	074	U+004A	J	j	106	0106	U+006A	j
K	75	075	U+004B	K	k	107	0107	U+006B	k
L	76	076	U+004C	L	l	108	0108	U+006C	l
M	77	077	U+004D	M	m	109	0109	U+006D	m
N	78	078	U+004E	N	n	110	0110	U+006E	n
O	79	079	U+004F	O	o	111	0111	U+006F	o
P	80	080	U+0050	P	p	112	0112	U+0070	p
Q	81	081	U+0051	Q	q	113	0113	U+0071	q
R	82	082	U+0052	R	r	114	0114	U+0072	r
S	83	083	U+0053	S	s	115	0115	U+0073	s
T	84	084	U+0054	T	t	116	0116	U+0074	t
U	85	085	U+0055	U	u	117	0117	U+0075	u
V	86	086	U+0056	V	v	118	0118	U+0076	v
W	87	087	U+0057	W	w	119	0119	U+0077	w
X	88	088	U+0058	X	x	120	0120	U+0078	x
Y	89	089	U+0059	Y	y	121	0121	U+0079	y
Z	90	090	U+005A	Z	z	122	0122	U+007A	z
[	91	091	U+005B	[	{	123	0123	U+007B	{
\	92	092	U+005C	\	\|	124	0124	U+007C	\|
]	93	093	U+005D	]	}	125	0125	U+007D	}
^	94	094	U+005E	^	~	126	0126	U+007E	~
_	95	095	U+005F	_	DEL	127	0127	U+007F
` (Grave)	96	096	U+005F	`

Text delimiters:

Character	Description	ASCII	ISO/IEC 8859-1 (Decimal)	Unicode (Hex)	HTML
‘ ’ ′ ʼ `	Left quote Apostrophe Prime LetterApostrophe Grave	96	096	U+2018 U+2019 U+2032 U+02BC U+005F	‘ ’ ′ ʼ `
“ ” ″				U+201C U+201D U+2033	“ ” ″
« »			0171 0187	U+00AB U+00BB	« »
‹ ›				U+3008 U+3009	&lsaquo; &rsaquo;
†				U+2020	&dagger;
‡				U+2021	&Dagger;
"		34	034	U+0022	"
#		35	035	U+0023	#
$		36	036	U+0024	$
%		37	037	U+0025	%
&		38	038	U+0026	&
'	Single quote	39	039	U+0027	'
¢	cent		0162	U+00A2	¢
£	Pound Sterling		0163	U+00A3	£
¤	Gen currency		0164	U+00A4	¤
€	Euro/EU		0164	U+20AC	€
¥	Yen		0165	U+00A5	¥

* The Unicode standard explicitly states that U+2019 is the preferred punctuation apostrophe.

Accents and Symbols

Character	ASCII	ISO/IEC 8859-1	Unicode (hex)	HTML
¦		0166	U+00A6	¦
§ (Section)		0167	U+00A7	§
´ (Acute) [resumé] á Á é É í Í ó Ó ú Ú ý Ý		0180 0225 / 0193 0233 / 0201 0237 / 0205 0243 / 0211 0250 / 0218 0253 / 0221	U+00B4 U+00E1 U+00C1 U+00E9 U+00C9 U+00ED U+00CD U+00F3 U+00D3 U+00FA U+00DA U+00FD U+00DD	&acute áÁ éÉ íÍ óÓ úÚ ýÝ
^ ˆ (Circumflex) [château] â Â ê Ê î Î ô Ô û Û	94	094 0226 / 0194 0234 / 0202 0238 / 0206 0244 / 0212 0251 / 0219	U+005E U+00E2 U+00C2 U+00EA U+00CA U+00EE U+00CE U+00F4 U+00D4 U+00FB U+00DB	&circ; â â ê Ê î Î ô Ô û Û
¨ (Umlaut/Dieresis) [naïve] ä Ä ë Ë ï Ï ö Ö ü Ü		0168 0228 / 0196 0235 / 0203 0239 / 0207 0246 / 0214 0252 / 0220	U+00A8 U+00C4 U+00C4 U+00EB U+00CB U+00EF U+00CF U+00F6 U+00D6 U+00FC U+00DC	¨ ä Ä ë Ë ï Ï ö Ö ü Ü
©		0169	U+00A9	©
™			U+2122	™
®		0174	U+00AE	®
` (Grave) [voilà] à À è È ì Ì ò Ò ù Ù	96	096 0224 / 0192 0232 / 0200 0236 / 0204 0242 / 0210 0249 / 0217	U+0060 U+00E0 U+00C0 U+00E8 U+00C8 U+00EC U+00CC U+00F2 U+00D2 U+00F9 U+00D9	(n.b. do not use the grave character as a left quote) à À è È ì Ì Ò Ò Ù Ù
˜ ∼ (Tilde) [mañana] ã Ã ñ Ñ õ Õ	126	0126 0227 / 0195 0241 / 0209 0245 / 0213	U+02DC U+007E U+00E3 U+00C3 U+00F1 U+00D1 U+00F5 U+00D5	&tilde; &sim; ã Ã ñ Ñ õ Õ
¸ (Cedilla) [façade] ç Ç		0184 0231 / 0199	U+00B8 U+00E7 U+00C7	¸ ç Ç

On the Apple Macintosh, diacritical marks (Acute,Circumflex,Umlaut,Grave,Tilde,) can be entered with Option + <e,i,u,`,n> followed by the letter to modify. So for example Option+i, A will produce Â.
Also Cedilla '¸'=Option+c and Eszett 'ß'=Option+s

Punctuation

Character	Description	ASCII	ISO/IEC 8859-1	Unicode	HTML
SP	Space Bar	32	032	U+0020
!		33	033	U+0021	!
(		40	040	U+0028	(
)		41	041	U+0029	)
*		42	042	U+002A	*
+		43	043	U+002B	+
,	Comma	44	044	U+002C	,
-	Hyphen/minus	45	045	U+002D	-
.	Full Stop/period	46	046	U+002E	.
…				U+2026	…
/		47	047	U+002F	/
:	Colon	58	058	U+003A	:
;	Semicolon	59	059	U+003B	;
<		60	060	U+003C	<
=		61	061	U+003D	&equiv;
>		62	062	U+003E	>
≤ ≥				U+2264 / U+2265	≤ ≥
?		63	063	U+003F	?
@		64	064	U+0040	@
[		91	091	U+005B	[
\		92	092	U+005C	\
]		93	093	U+005D	]
^	Caret	94	094	U+005E	^
_		95	095	U+005F	_
{		123	0123	U+007B	{
\|		124	0124	U+007C	\|
}		125	0125	U+007D	}
DEL	Delete	127	0127	U+007F
	non breaking Space		0160	U+00A0
¡	Inverted Exclamation		0161	U+00A1	¡
ª	feminine ordinal		0170	U+00AA	ª
¬	NOT sign		0172	U+00AC	¬
	soft hyphen (SHY)		0173	U+00AD
¯	Macron accent		0175	U+00AF	¯
°			0176	U+00B0	°
±			0177	U+00B1	±
µ	Micro		0181	U+00B5	µ
¶	Paragraph		0182	U+00B6	¶
·	middle dot		0183	U+00B7	·
•	Bullet/Beep	7		U+2022	•
¸	Cedilla		0184	U+00B8	¸
º	Masculine Ordinal		0186	U+00BA	º
¿	Inverted question mark		0191	U+00BF	¿
ß	Eszett		0223	U+00DF	ß
–	ndash			U+2013	–
—	mdash			U+2014	—
―	quotation dash			U+2015
String Terminator				U+009C
π	PI			U+203B	π
← → ↑ ↓				U+2190 U+2192 U+2191 U+2193	← → ↑ ↓
☺	Smiley			U+263A	☺
℮ or ℮	Estimated			U+212e	℮ or ℮

Greek Alphabet

Character		Unicode	HTML
Α α	Alpha	U+2C6D / U+0251	Ɑ (Ɑ) / ɑ (ɑ)
Β β	Beta	U+0392 / U+03B2	Β (Β) or Β (Β) β (β) or β (β)
Γ γ	Gamma	U+0393 / U+03B3	Γ (Γ) or Γ (Γ) γ (γ) or γ (γ)
Δ δ	Delta	U+0394 / U+03B4	Δ (Δ) or Δ (Δ) δ (δ) or δ (δ)
Ε ε	Epsilon	U+0395 / U+03B5	Ε (Ε) or Ε (Ε) ε (ε) or ε (ε)
Ζ ζ	Zeta	U+0396 / U+03B6	Ζ (Ζ) or Ζ (Ζ) ζ (ζ) or ζ (ζ)
Η η	Eta	U+0397 / U+03B7	Η (Η) or Η η (η) or η
Θ θ	Theta	U+0398 / U+03B8	Θ (Θ) or Θ θ (θ) or θ
Ι ι	Iota	U+0399 / U+03B9	Ι (Ι) or Ι ι (ι) or ι
Κ κ	Kappa	U+039A / U+03F0	Κ (Κ) or Κ κ (κ) orκ
Λ λ	Lambda	U+039B / U+03BB	Λ (Λ) or Λ λ (λ) or λ
Μ μ	Mu	U+039C / U+03BC	Μ (Μ) or Μ μ (μ) or μ
Ν ν	Nu	U+039D / U+03BD	Ν (Ν) or Ν ν (ν) or ν
Ξ ξ	Xi	U+039E / U+03BE	Ξ (Ξ) or Ξ ξ (ξ) or ξ
Ο ο	Omicron	U+039F / U+03BF	Ο (Ο) or Ο Ο (ο) or ο
Π π	Pi	U+03A0 / U+03C0	Π (Π) or Π π (π) orπ
Ρ ρ	Rho	U+03A1 / U+03F1	Ρ (Ρ) or Ρ (Ρ) ρ (ρ) or ρ (ρ) ϱ (ϱ)
Σ σ ς	Sigma	U+03A3 / U+03C3 / U+03C2	Σ (Σ) or Σ (Σ) σ (σ) or σ (σ) ΢ (΢) / ς (ς)
Τ τ	Tau	U+03A4 / U+03C4	Τ (Τ) or Τ (Τ) τ (τ) or τ (τ)
Υ υ	Upsilon	U+03A5 / U+03C5	Υ (Υ) or Υ (Υ) υ (υ) or υ (υ)
Φ φ	Phi	U+03A6 / U+03C6	Φ (Φ) or Φ (Φ) φ (φ) or φ (φ)
Χ χ	Chi	U+03A7 / U+03C7	Χ (Χ) or Χ (Χ) χ (χ) or χ (χ)
Ψ ψ	Psi	U+03A8 / U+03C8	Ψ (Ψ) or Ψ (Ψ) ψ (ψ) or ψ (ψ)
Ω ω	Omega	U+03A9 / U+03C9	Ω (Ω) or Ω (Ω) Ω (ω) or ω (ω)

Control codes

Character	ASCII	Unicode	HTML
NUL (Null)	0	U+0000
SOH (Start of heading)	1	U+0001	<h1>
STX (Start of text)	2	U+0002	<body>
ETX (End of text)	3	U+0003	</body>
EOT (End of transmit)	4	U+0004
ENQ (Enquiry)	5	U+0005
ACK (Acknowledgment)	6	U+0006
BEL (Audible bell)	7	U+0007
BS (Backspace)	8	U+0008
HT (Horizontal tab)	9	U+0009
LF (Line feed)	10	U+000A
VT (Vertical tab)	11	U+000B
FF (Form feed)	12	U+000C
CR (Carriage return)	13	U+000D	<br>
SO (Shift out)	14	U+000E	<blockquote>
SI (Shift in)	15	U+000F	</blockquote>
DLE (Data link escape)	16	U+0010
DC1 (Device control 1)	17	U+0011
DC2 (Device control 2)	18	U+0012
DC3 (Device control 3)	19	U+0013
DC4 (Device control 4)	20	U+0014
NAK (Neg. acknowledge)	21	U+0015
" SYN (Synchronous idle)	22	U+0016
ETB (End trans. block)	23	U+0017
CAN (Cancel)	24	U+0018
EM (End of medium)	25	U+0019
SUB (Substitution)	26	U+001A
ESC (Escape)	27	U+001B
FS (File separator/Figure shift)	28	U+001C
GS (Group separator)	29	U+001D	<div>
RS (Record separator)	30	U+001E
US (Unit separator)	31	U+001F

n.b. The first 256 Unicode values represent the same characters as ISO 8859-1
The complete unicode character set runs to over 90,000 entries.

Entering character codes at the terminal:

In Windows to input a 4 digit decimal ISO/IEC code, hold down the ALT key, type e.g. 0164 on the numeric keypad, then release ALT.

In bash type echo $'\xNN' where NN is a two digit (hex) unicode, this covers the Hex values 20 to 7e as shown below:

<space>!"#$%&'()*+,-./0123456789 :;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ [\]^_` abcdefghijklmnopqrstuvwxyz{|}~

bash will also accept the following special characters with Alt-key and Alt-Shift-key combinations:

¡¢£¤¥¦§¨©ª«¬®¯°±²³´µ¶·¸¹º»¼½¾ ¿ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓ ÔÕÖ×ØÙÚÛ ÜÝ Þßàáâãäåæçèéêëìíîïð ñòóôõö÷ø ùúûüýþÿ
(equivalent to Hex A1-FF)

Extended Ascii Characters
At one time there were many versions of the extended ASCII set (128-255), used to provide (limited) foreign language and graphics support, this is the most popular set. These are not compatible with ISO or unicode and are no longer used in modern systems.

“Smart data structures and dumb code works a lot better than the other way around” – Eric S. Raymond

Related:

Symbols, smilies and box drawing characters
Ascii/Unicode table in numeric order
Graphemica - Search for Unicode characters
Shapecatcher - Find unicode by drawing
Convert Unicode # to css / javascript #
Unicode Slide Rule
DecodeUnicode - Explains what the symbols mean (Wiki)
Ishida's online unicode converter
The UnicodeInput Utility for Windows
Quotation marks in different languages - Wikipedia
FileFormat.info - Unicode characters
Wikipedia - Unicode characters
MS Office Unicode