Cursor

A cursor is a movable marker that indicates a position. The term has been used with this meaning since the 16th century, for a wide variety of movable position markers.

Slide rule cursor

On slide rules, a cursor is a sliding glass or plastic plate that has a fine line etched or painted onto it to line up the different scales. Slide rule operation consists of finding a number on one scale and lining it up with a number on another scale. If the scales a separated by any distance, the cursor is used to accurately line them up or read values.

On a typewriter, the cursor indicates the position at which the next key to be struck will type.

In database packages, cursor refers to a control structure for the traversal of records returned by a query.

The term is now most commonly used as a feature of a computer user interface. On CRT character-based interfaces, the cursor was originally (and is still sometimes) a solid rectangle indicating the position of the next character to be typed or the next to be deleted when backspacing or overtyping. On modern computers with a graphical user interface, there are two cursors: when editing text, a cursor called an insertion point is displayed to show the location of any modifications. This is usually represented by a blinking vertical line. The other cursor is the mouse pointer, usually an arrow that moves on the screen as you move the mouse on your desk.

In many computer programs, the shape of the cursor changes when the user's task changes. For instance:

A text-insertion cursor is displayed while the user is writing something.
In text that cannot be edited but can be selected, for example, on a web page, the cursor can also be a vertical bar, possibly with little cross bars at the top and bottom.
When the cursor hovers over a hyperlink, it changes into a hand with a stretched index finger. Also often some informative text about the link pops up, not in a regular window, but in a special hover box, which disappears when the cursor is moved away. The HTML code is
```
link label
```
In move mode (for moving an image or icon), the cursor is a hand with all fingers stretched.
A graphics-editing cursor is displayed while the user is editing an image.
On an edge of a window the cursor changes into a double arrow (horizontal, vertical, or diagonal) indicating that the edge can adjusted in the indicated direction.
When a computer process is performing tasks and is unable to accept user input, a wait cursor (an hourglass or watch) is sometimes displayed in the corresponding window.