# What does "\!" aka backslash exclamation mark do?

I don't know what the commands `\!`

are supposed to do in the code you show, other than raising *many* errors.

The command `\!`

is only allowed in math mode (unless redefined, which I'd discourage). It's purpose is to insert a *negative thin space*, which is useful in several places. For instance

```
\biggl(\frac{121}{12}-1\biggr)^{\!2}
```

is an improvement over `^{2}`

, because it moves the exponent towards the parenthesis and takes care of its bending.

Another place where it is helpful is in `2/\!\log x`

, because for technical reasons `/`

is an ordinary symbol and TeX would add a thin space between it and the “log” operator.

Here's a picture: left the output with `\!`

, right without.

The negative spacing of `\!`

exactly matches the positive one by `\,`

(which is automatically inserted in some places) in math mode. Note that `\,`

can be used outside of math mode, where it inserts a sixth of a quad of space.

If you want to tighten a table, reduce the size of `\tabcolsep`

. Using explicit negative spaces all over the place is not the correct way.

And ** never** use

`\resizebox`

on a table.This symbol is usually defined as

```
\! negative thin space (normally 1/6 of a quad)
```

It is commonly used in tables, and formulas among other ways to manipulate spaces in LaTeX

And before you do post a question, please do run a search with similar keywords on this site. Hope this helps.