Navigation possibilities with 5 different items

Question

How many possibilities does a navigation have with 5 different items.

I first though of 5x5 but that is not enough I think.

For example, these are some possibilities:

The letters represent simple navigation text items like Home, Users, Login ...

A

B

C

D

E

A     B     C     D     E

A     B     C     D

A     B     C 

A     B  

A   
...

if I have for example this:

A    B

and

B    A

it is redundant in my case, the order is not important.

Answer 1

The number of ways to select $m$ elements from a set of $N$ elements is given by the combinatorial number $N \choose m$.

So the number of combinations of 1 to 5 elements from a set of 5 elements is:

$$\sum_{i=1}^5 {5 \choose i}=31$$

Answer 2

The number of different locations you can reach with $n$ navigation directions is

$$^nC_1+ ^nC_2+...+^nC_n=(1+1)^n-1=2^n-1$$