Give a sorted list of distinct elements:

Give a sorted list of distinct elements from all the lists:

Enter using un:

Give a list of the distinct lists:

Union works with any head, not just List:

Find divisors that occur in any of 10, 12, and 20:

Find all the triples of bits that occur in the binary decomposition of 10!:

Find the distinct elements in the iteration:

Find what options are used by a list of functions:

Split on the sorted set gives lists of the same elements:

The union is equivalent to the first elements of these lists:

Tally gets the count of identical elements and returns them in the original order:

The union is the sorted list of the elements returned by Tally:

DeleteDuplicates is similar to Union without sorting:

Avoiding the sort improves the speed substantially:

For large sets Union may be slow with SameTest since it requires all pairwise comparisons:

When equivalence class representatives can be found, it may be faster to use Union on these:

The results are the same except for the choice of representative: