Question: If I have a list 

```
list={3,7,4,5,1}

```

how to get the List of Intervals /Ranges

```
result = {{1,3},{3,4},{4,5},{5,7}}

```

Answer: 
Maybe

```
Partition[Sort@list, 2, 1]

```

giving

> 
> {{1, 3}, {3, 4}, {4, 5}, {5, 7}}
> 
> 
>
Tom's answer is canonical, but you could also use:

```
With[{s = Sort[list]}, Transpose[{Most[s], Rest[s]}]]

```

which seems to be marginally faster for large lists. (In which case most of the time is spent sorting.)