The American Standard Code for Information Interchange includes a set of commands for synchronization of communicating devices and for formatting text.

The commands of the ASCII code are:

Val	Cmd	Description
0	NUL	Null character, commonly used in communications for bit synchronization.
1	SOH	Start of Heading.
2	STX	Start of Text.
3	ETX	End of Text.
4	EOT	End of Transmission. A Signoff.
5	ENQ	ENQuiry, a request for status of a communicating device.
6	ACK	ACKnowledge, a common reply to ENQ, indicating that current conditions are satisfactory.
7	BEL	Bell. The receiving device should make a noise.
8	BS	Back Space. Moves the current position to the left or decrements the position counter. Backspace may be destructive (i.e the character at the new position is deleted) or non-destructive (only implies a change in position). When BS is non-destructive, the destructive version is accomplished by the sequence BS/DEL.
9	HT	Horizontal tab. Move horizontally to the next TAB stop before displaying/printing the next character.
10	LF	Line feed. Move to the next row before displaying/printing the next character. In the strictest sense, this command requires that the row counter is to be incremented, with no change in the column position.
11	VT	Vertical Tab. Move down a number of rows (to the next Vertical tab stop) before printing/displaying the next character.
12	FF	Form Feed. Advance to the top of the next page(or screen).
13	CR	Carriage Return. Move to left edge of the current row (i.e. set the column position to zero) before printing/displaying the next character.
14	SO	Shift Out. The SO/SI commands are vestigial elements of the older Baudot code, which used only five binary digits for recording the character value and was a predecessor to ASCII. Teletype machines commonly used the Baudot code to communicate text.
15	SI	Shift In. In the Baudot code, most values could represent two different graphics. Which one of the two was intended was determined by the status of the shift mechanism, which could be either in (i.e. engaged) or out (i.e. disengaged).
16	DLE	Data Link Escape.
17	DC1	Data Control #1. This is also known as XON, transmitted by the receiving end of a connection to indicate that transmission may resume.
18	DC2	Data Control #2.
19	DC3	Data Control #3. This is also known as XOFF, transmitted by the receiving end of a connection to indicate that transmission should be temporarily suspended.
20	DC4	Data Control #4.
21	NAK	Negative Acknowledge. Most commonly, a disappointing reply to an ENQ, indicating that the status of the device transmitting the NAK is less than satisfactory.
22	SYN	Synchronous Idle.
23	ETB	End ot Text Block.
24	CAN	Cancel.
25	EM	End of medium.
26	SUB	Substitute.
27	ESC	Escape.
28	FS	File Separator.
29	GS	Group Separator.
30	RS	Record Separator.
31	US	Unit Separator.
32	SP	Space. Move to the right one column before printing/displaying the next character.
127	DEL	Delete (or Rubout). Deletes the character at the current position.

Codes 33 - 126 are for the graphic characters.