What Does Cellspacing Mean?
Cellspacing is a command attribute that involves setting a number of pixels between each cell in a table.
Techopedia Explains Cellspacing
In cellspacing, a designer can increase the size of the borders in a table without increasing the margin of what is inside a text box. This is not to be confused with cellpadding, which actually changes the amount of margin inside each cell or box to create more white space around the text area.
One of the most common uses of cellspacing is in Web design. Here, designers can use Cascading Style Sheets (CSS) to change spacing with a "border-spacing" command. Other technologies have their own syntax and commands for increasing cellspacing and for changing the appearance of tables or spreadsheet cells.