# Using \\[<dim>] in tabular environment

In a tabular environment what does \\[<dim>] do? Does that set the font size for the following line or for the current line? See example below?

\begin{tabular}{| c | c |}
words & more words \\[6pt]
stuff & other stuff \\
\end{tabular}

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Change 6pt to 50pt, its pretty clear what it does. –  Nicholas Hamilton May 4 at 13:00
It adds 6pt of vertical space below the row. –  egreg May 4 at 13:00
Thank you. What is the default then? –  maggick May 4 at 13:01
@maggick Just use \\ –  egreg May 4 at 13:02

\\[6pt]

Makes a forced line break with 6pt of additional space. But you should almost never use \\ in normal text with or without this option.
In tabular (and array etc) it is similar but the amount of extra vertical space that added is sometimes surprising. What it actually does is to add 6pt more to the minimum depth of the current row, by adding a strut of that depth (that is a rule with 0pt width but depth 6pt more than the default strut. This means that a normal row gets additional space below it but if the row already has entries with large depth (for example, vertically centred images) then increasing the minimum depth of the row will do nothing.