For questions related to the "internal SDcard" used by some Android devices to increase the amount of available storage. For the external micro-SDcard, use 'external-sd'. See the 'storage' tag wiki for a full overview of available storage-related tags.
Most newer Android devices ship with a so-called "internal SDCard" to increase storage available for data and apps. Some don't even support an external-sd anymore (especially the newer Nexus devices).
The term "internal SDCard" is very misleading and confusing, as a) a SDCard is per definitionem removable (see also the Secure Digital Wikipedia article for details on SDCards), and b) if you dismantle those devices, you won't find a SDCard inside at all. In most cases, the storage called "internal SDCard" resides on the very same chip holding the internal-storage (or "internal Flash memory" -- next confusion, as this not necessarily refers to RAM but storage). Not infrequently, internal storage (including the "internal SDCard") uses eMMC instead, which stands for "embedded MultiMediaCard".