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In computing, a cursor is an indicator used to show the position on a computer monitor or other display device that will respond to input from a text input or pointing device. The flashing text cursor may be called a caret, as in caret browsing. The mouse cursor is also called a pointer, owing to its arrow shape on some systems.
Cursor is Latin for 'runner.' A cursor is the name given to the transparent slide engraved with a hairline that is used for marking a point on a slide rule. The term was then transferred to computers through analogy.
In most command-line interfaces or text editors, the text cursor or caret navigation, is an underscore, a solid rectangle, or a vertical line, which may be flashing or steady, indicating where text will be placed when entered (the insertion point). In text mode displays, it was not possible to show a vertical bar between characters to show where the new text would be inserted, so an underscore or block cursor was used instead. In situations where a block was used, the block was usually created by inverting the pixels of the character using the boolean math exclusive or function. On text editors and word processors of modern design on bitmapped displays, the vertical bar is typically used instead.
The blinking of the text cursor is usually temporarily suspended when it is being moved; otherwise, the cursor may change position when it is not visible, making its location difficult to follow.
Some interfaces use an underscore or thin vertical bar to indicate that the user is in insert mode, a mode where text will be inserted in the middle of the existing text, and a larger block to indicate that the user is in overtype mode, where inserted text will overwrite existing text. In this way, a block cursor may be seen as a piece of selected text one character wide, since typing will replace the text "in" the cursor with the new text.
A vertical line text cursor with a small left-pointing or right-pointing appendage are for indicating the direction of text flow on systems that support bi-directional text, and is thus usually known among programmers as a 'bidi cursor'. In some cases, the cursor may split into two parts, each indicating where left-to-right and right-to-left text would be inserted.
The idea of a cursor being used as a marker or insertion point for new data or transformations, such as rotation, can be extended to a 3D modeling environment. Blender, for instance, uses a 3D cursor to determine where future operations are to take place.
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