Definition - What does Gridlines mean?
Gridlines are the light gray lines which separate the cells, rows and columns on a spreadsheet, which is commonly used in computational software for keeping records of data. Microsoft Excel and Google Spreadsheet are two of the most well-known applications that use gridlines.
Techopedia explains Gridlines
Spreadsheet gridlines are normally lightly colored horizontal and vertical lines that appear around cells in a worksheet. These gridlines are used to define the boundaries of cells, columns, and rows in a worksheet. Gridlines can be customized, with their color, thickness and even pattern all options that can be specified by the user. If they are to be printed, it must be specified in settings to do so, because gridlines normally do not print by default.