Does difficulty change between rounds?

[Peripeteia]

Obviously a noob question. I thought difficulty was constant between rounds.

However I found a difficulty estimate here: http://dot-bit.org/tools/nextDifficulty.php which has estimates for the last round, the next round, and the "instant" blocks currently being processed. It's this instant part that's confusing me as its difficulty fluctuates.

Thanks for enlightening me!

[Elokane]

I believe "Instant" is the difficulty increase that would take place based on the current block-find rate. It doesn't take into account the average find-rate since the last change.
E.g. find rate is 7.2 blocks/hour -> instant difficulty is 20%.

[Maxim Gladkov]

Nope.