Unbiased random numbers
Simple generators often use Math.random with multiplication and rounding, which can make some numbers slightly more likely than others. This generator draws from the secure random generator of your browser and rejects values that would cause a bias, so every number in the range has exactly the same chance.
Both the minimum and the maximum are included. With Unique on, no number appears twice; asking for more unique numbers than the range holds gives a clear message instead of a wrong result.
Lotteries, samples and games
Draw lottery style numbers, pick a random sample of rows to check in a spreadsheet, choose question numbers for a quiz or generate test data. Sorted output makes long lists easy to read, and Copy puts one number per line on your clipboard.