Display apparatus for providing preview UI and method of controlling display apparatus

A display apparatus comprising:

• a display;
• a touch input interface configured to sense a touch input;
• and
• a processor configured to:
• control the display to display a first pages;
• based on a first touch input being sensed through the touch input interface while the first page is displayed, control the display to display the first page and a preview user interface comprising a plurality of preview pages respectively corresponding to the plurality of pages including the first page, wherein each of the plurality of preview pages is smaller than the first page;
• and
• based on a second touch input being sensed on a first preview page corresponding to the first page among the plurality of preview pages through the touch input interface while the first page and the plurality of preview pages are displayed, control the display to revise a content of the first page corresponding to the first preview page on which the second touch input is sensed by inserting writing content into the first page, according to the second touch input.