ASCII: What is It and Why Should I Care?

ASCII:
What is It and Why Should I Care?

ASCII, pronounced "ask-ee" is the acronym for American Standard Code for Information Interchange. It's a set of characters which, unlike the characters in word processing documents, allow no special formatting like different fonts, bold, underlined or italic text. All the characters used in email messages are ASCII characters and so are all the characters used in HTML documents. (Web browsers read the ASCII characters between angle brackets, "<" and ">", to interpret how to format and display HTML documents.)

An "ASCII file" is a data or text file that contains only characters coded from the standard ASCII character set. Characters 0 through 127 comprise the Standard ASCII Set and characters 128 to 255 are considered to be in the Extended ASCII Set. These codes, however, may not be the same in all computers and files containing these characters may not display or convert properly by another ASCII program.

Knowing something about ASCII can be helpful. ASCII files can be used as a common denominator for data conversions. For example, if program A can't convert its data to the format of program B, but both programs can input and output ASCII files, the conversion may be possible.

ASCII characters are the ones used to send and receive email. If you're familiar with email, you already know that formatting like italic type and underlines are not possible. Email transmissions are limited to ASCII characters and because of that, graphics files and documents with non-ASCII characters created in word processers, spreadsheet or database programs must be "ASCII-fied" and sent as email file attachments. When the files reach their destination they are "deASCII-fied" (i.e. decoded) and therefore, reconstructed to restore them for use.

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Standard ASCII

The first 32 characters (0-31) are control codes.

ASCII			Description
0		NUL	Null
1		SOH	Start of heading
2		STX	Start of text
3		ETX	End of text
4		EOT	End of transmit
5		ENQ	Enquiry
6		ACK	Acknowledge
7		BEL	Audible bell
8		BS	Backspace
9		HT	Horizontal tab
10		LF	Line feed
11		VT	Vertical tab
12		FF	Form feed
13		CR	Carriage return
14		SO	Shift out
15		SI	Shift in
16		DLE	Data link escape
17		DC1	Device control 1
18		DC2	Device control 2
19		DC3	Device control 3
20		DC4	Device control 4
21		NAK	Neg. acknowledge
22		SYN	Synchronous idle
23		ETB	End trans. block
24		CAN	Cancel
25		EM	End of medium
26		SUB	Substitution
27		ESC	Escape
28		FS	Figures shift
29		GS	Group separator
30		RS	Record separator
31		US	Unit separator
32		SP	Blank Space (Space Bar)
ASCII		DISPLAY
33		!
34		"
35		#
36		$
37		%
38		&
39		'
40		(
41		)
42		*
43		+
44		,
45		-
46		.
47		/
48		0
49		1
50		2
51		3
52		4
53		5
54		6
55		7
56		8
57		9
58		:
59		;
60		<
61		=
62		>
63		?
64		@
65		A
66		B
67		C
68		D
69		E
70		F
71		G
72		H
73		I
74		J
75		K
76		L
77		M
78		N
79		O
80		P
81		Q
82		R
83		S
84		T
85		U
86		V
87		W
88		X
89		Y
90		Z
91		[
92		\
93		]
94		^
95		_
96		`
97		a
98		b
99		c
100		d
101		e
102		f
103		g
104		h
105		i
106		j
107		k
108		l
109		m
110		n
111		o
112		p
113		q
114		r
115		s
116		t
117		u
118		v
119		w
120		x
121		y
122		z
123		{
124		|
125		}
126		~
127