What is meant by ^1 as array index (e.g. arr[^1]) in C#?

C# 8.0 and going forward, declared the new ranges and indexes

Among them the ^ operator:

Let's start with the rules for indices. Consider an array sequence. The 0 index is the same as sequence[0]. The ^0 index is the same as sequence[sequence.Length].

So it a way to search an indexable object in reverse, without needing to iterate like sequence[sequence.Length - i].

string[] words = new string[]
{
                // index from start    index from end
    "The",      // 0                   ^9
    "quick",    // 1                   ^8
    "brown",    // 2                   ^7
    "fox",      // 3                   ^6
    "jumped",   // 4                   ^5
    "over",     // 5                   ^4
    "the",      // 6                   ^3
    "lazy",     // 7                   ^2
    "dog"       // 8                   ^1
};              // 9 (or words.Length) ^0