These inks are "regular fountain pen ink" – water-soluble, dye-based inks. That means they're suitable for beginners and advanced fountain pen users alike, usable in modern mainstream fountain pens without any special caution.
This means that these inks are not pigment inks, iron-gall inks, or otherwise "permanent" or waterproof inks, which are a bit less beginner friendly and require more special care (or at least more frequent fountain pen cleaning).
