Cursor (user interface)

In human–computer interaction, a cursor is an indicator used to show the current position on a computer monitor or other display device that will respond to input, such as a text cursor or a mouse pointer.

Cursor is Latin for 'runner'. A cursor is a name given to the transparent slide engraved with a hairline used to mark a point on a slide rule. The term was then transferred to computers through analogy.

On 14 November 1963, while attending a conference on computer graphics in Reno, Nevada, Douglas Engelbart of Augmentation Research Center (ARC) first expressed his thoughts to pursue his objective of developing both hardware and software computer technology to augment human intelligence by pondering how to adapt the underlying principles of the planimeter to inputting X- and Y-coordinate data, and envisioned something like the cursor of a mouse he initially called a bug, which, in a 3-point form, could have a "drop point and 2 orthogonal wheels". He wrote that the "bug" would be "easier" and "more natural" to use, and unlike a stylus, it would stay still when let go, which meant it would be "much better for coordination with the keyboard."

According to Roger Bates, a young hardware designer at ARC under Bill English, the cursor on the screen was for some unknown reason also referred to as CAT at the time, which led to calling the new pointing device a mouse as well.

In most command-line interfaces or text editors, the text cursor, also known as a caret, 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.

In a typical text editing application, the cursor can be moved by pressing various keys. These include the four cursor keys, the Page Up and Page Down keys, the Home key, the End key, and various key combinations involving a modifier key such as the Control key. The position of the cursor also may be changed by moving the mouse pointer to a different location in the document and clicking.

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.

The concept of a blinking cursor can be attributed to Charles Kiesling Sr. via US Patent 3531796, filed in August 1967.