When you create a new qube, you don't copy the whole system needed for this qube to work (which would include copying all the programs).
Instead, each qube *shares* the system with its respective template.
A qube has read-only access to the system of the template on which it's based, so a qube cannot modify a template in any way.
This is important, as it means that if a qube is ever compromised, the template on which it's based (and any other qubes based on that template) will still be safe.
So, creating a large number of qubes is cheap: each one needs only as much disk space as is necessary to store its private files (e.g., the "home" folder).
If you've installed Qubes OS using the default options, a few qubes have already been created for you:
Most Qubes OS users associate red with what's untrusted and dangerous (like a red light -- stop! danger!), green with what's safe and trusted, and yellow and orange with things in the middle.
This color scheme also extends to include blue and black, which are usually interpreted as indicating progressively more trusted domains than green, with black being ultimately trusted.
However, it's totally up to you how you'd like to interpret these colors.
Qubes OS doesn't assume anything about these colors.
When you make a new qube, the system doesn't do anything special to it depending on whether it's black or red, for example.
The only difference is which color you see and the meaning you assign to that color in your mind.
For example, you could use the colors to show that qubes belong to the same domain.
You might use three or four qubes for work activities and give them all the same distinct color label, for instance.
In addition to qubes and templates, there's one special domain called [dom0](/doc/glossary/#dom0), where many system tools and the desktop manager run.
In particular, [you should never run user applications in dom0](https://github.com/Qubes-Community/Contents/blob/master/docs/security/security-guidelines.md#dom0-precautions).
For an overview of the entire system, you can use the **Qube Manager** (go to the Application Launcher → System Tools → Qube Manager), which displays the states of all the qubes in your system.
It's a good idea to start out with the three qubes created automatically by the installer: work, personal, and untrusted.
If and when you start to feel that some activity just doesn't fit into any of your existing qubes, or you want to partition some part of your life, you can easily create a new qube for it.
You might find it helpful to read [this article](https://blog.invisiblethings.org/2011/03/13/partitioning-my-digital-life-into.html), which describes how one of the Qubes OS architects partitions her digital life into security domains.
<p>Make sure your hardware is compatible, as Qubes OS cannot run on every type of computer. Also, check out <ahref="/doc/certified-laptops/">Qubes-certified Laptops</a>.</p>
<p>Download an ISO, learn how to verify its authenticity and integrity, and follow our guides to install Qubes OS. Looking for the source code? You'll find it on <ahref="https://github.com/QubesOS">GitHub</a>.</p>
<p>Peruse our extensive library of documentation for users and developers of Qubes OS. You can even help us <ahref="/doc/doc-guidelines/">improve</a> it!</p>
