Grave accents instead of '' in mysqli_query

Grave accents instead of '' in mysqli_query

I have a problem, I looked for it on google, couldn't find it.
$result = mysqli_query($link,"SELECT * FROM update ");
Error
Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result,
boolean given in
When I change the query to:
$result = mysqli_query($link,"SELECT * FROM `update` ");
It works. Why is that?