Multi-path autocomplete (formely known as Menu path autocomplete) changes some input field for entering paths to an autocomplete text field so users do not need to know the internal system path but simply can enter the title of the page to link to.
Currently these sections are altered:
* adding or editing a menu item
* adding or editing an url alias (>= Drupal 7)
* adding or editing a shourtcut item (Drupal 7 only at the moment)
While entering characters into this field you will get a list of all matching node titles (and - if path is enabled - all matching URL aliases). Selecting one item will insert the internal link to it.
* Version 7.x is named "Multi path autocomplete" because it doesn't alter fields for menu paths only.
* Version 8.x is now (finally) named "Multi-path autocomplete"
Development on Multi-path autocomplete is sponsored by undpaul