Sqrt[z] or gives the square root of z.
Mathematical function (see Section A.3.10).
can be entered using 2z or \(\@z\).
Sqrt[z] is converted to z^(1/2).
Sqrt[z^2] is not automatically converted to z.
Sqrt[a b] is not automatically converted to Sqrt[a] Sqrt[b].
These conversions can be done using PowerExpand, but will typically be correct only for positive real arguments.
In StandardForm, Sqrt[z] is printed as .
z can also be used for input. The character is entered as sqrt or \[Sqrt].
See The Mathematica Book: Section 1.1.3.
See also: Power, PowerExpand, SqrtBox.