When a person wanted to type a table (of numbers or text) on a typewriter, there was a lot of time-consuming and repetitive use of the space bar and backspace key.
For numeric data, however, the logical place for the tab stop is the location of the least significant digit.
Tabbing to this location and then pressing the backspace key to back up to the position of the first digit is practical but slow.
On some systems, even if your input is ambiguous, tab completion may give you a list of possible options to select from.
Some programmers and programming languages prefer the usage of multiple whitespace characters instead for that purpose.
This was done horizontally with movable metal prongs in a row, and vertically with a loop of mylar or other tape the length of a page with holes punched in it to indicate the tab stops.
Despite the fact that five characters were the typical paragraph indentation on typewriters at that time, the horizontal tab size of eight evolved because as a power of two it was easier to calculate with the limited digital electronics available.
[7] Modern text editors usually have the Tab key insert the user-defined indentation and may use heuristics to adapt this behavior to existing files.
Text divided into fields delimited by tabs can often be pasted into a word processor and formatted into a table with a single command.
TSV has also been cited in a modern approach to solving the programming debate regarding the use of tabs and spaces for code alignment called elastic tabstops.
In HTML the horizontal tab is coded using or [9][10] but as with all whitespace characters in HTML, this will be displayed as a single space except inside
, tags (or other elements with CSS attribute white-space set to pre).
CSS3 defines tab-size property, which adjusts the number of spaces for the tab character from the default of eight.
[12] The vertical tab is but is not allowed in SGML[citation needed]; this includes XML 1.0[13] and HTML.
