[Japo]

It all depends on the settings. The default ones after a default installation are designed to make it less noisy. Even the HIPS, since those are remarkable for their noisiness. But true not everybody will want a HIPS even a not so noisy one, although it adds a great deal of security for the paranoid out there. You can opt out the HIPS during installation.

The default setting for the firewall is "train with safe mode". In this setting it allows (and remembers creating rules) for programs within Comodo's database of "safe" ones. If you want the traditional, noisier setting where you're asked about every new access, change the setting to "custom policy mode". Also there's a "training mode" which you can select temporarily so you don't have to deal with popups, it allows and remembers for every new access, so it's designed to be selected when you're certain that only legit acesses will take place, so that the rules are created automatically and you don't have to worry about it.

The HIPS, since it's more likely to overwhelm a user with popups, has an additional setting between "train with safe mode" and "training mode", called "clean PC mode". It's like "train with safe" only that all the programs installed in your computer before CFP was installed, scanned at the time of installation, are considered safe, not only the ones in Comodo's database. So if your computer was already clean when you installed CFP, this setting will keep it that way the same that the "train with safe mode", and you will be asked only about newly installed programs. Also when you run an installer you can answer the popup by "treating as installer", then you're asked if you want to temporarily switch to "installing mode", then the installed files will be trusted in the future; after a while CFP prompts for you to swtich back from installing mode.

Another nice feature of Defense+ (the HIPS) is that it can protect programs from termination, since many malware try to kill your antivirus before they attack elsewhere. So you no longer must rely on each and every of your security programs to be strong against maliciuos termination, you can make D+ defend them all. It also can defend important files and the Windows registry from malicious modification.

But if you're interested about how it works and its full features you should read its help file, it's very informative.