"Kali is a rolling Linux distribution,..." What that means? is it Debian Linux derivative?

Q1.
At:
https://www.kali.org/get-kali/#kali-installer-images
says:
"Kali is a rolling Linux distribution,..."
What that means? is it Debian Linux derivative?

Q2.
Every when Kali Linux is updating their installing ISOs, VM prebuilt images, etc...?

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Installer Images

Kali is a rolling Linux distribution, meaning as soon as we have an update, we ship it. Would-be users have a variety of images to choose from. For more information, please see Which Image Should I Download? and Kali Branches. For most users, we recommend the latest ?point release? image below, except in cases when a user requires a specific bug patch, in which case the weekly build may be best.
We generate fresh Kali Linux image files every quarter. These become the official "point" releases. These images are tested and subsequently announced with a blog post.
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A rolling Linux distribution is a distribution that provides a continuous stream of updates and upgrades to the user. This means that new packages are released as soon as they are available, rather than waiting for a new version of the distribution to be released.There are a few advantages to using a rolling Linux distribution. First, you always have the latest security updates and bug fixes. Second, you don't have to worry about upgrading your distribution every few months. Third, rolling distributions tend to be more stable than traditional distributions, as they are constantly being patched and updated.

Kali Linux is a rolling distribution that is based on Debian. This means that it inherits all of the stability and security features of Debian, while also providing the latest security updates and bug fixes.