What is exponentiation?

A $log$ function can be written as follows

If

$\log_{a}$ b = $x$

Then

$a^{x}$ = b

When the question is stated as above, we are looking for the power in which we should raise 2 to get 256 .

$2^{x}$ = 256

$x$ = 8

Therefore

$\boxed{\log_{2}256 = 8}$

$\large \log_2 256 = \log_2 (2^8) = 8 \log_2 (2) = 8 \times 1 \implies \boxed{8}$