Action is about conflict. Whether with guns, blades, fists, or mysterious powers, these anime feature characters in combat - either to protect themselves or the things or people they value, or simply as a way of life.
Fantasy anime take place in a broad range of settings influenced by mythologies, legends, or popular and defining works of the genre such as The Lord of the Rings. They are generally characterized by a low level of technological development, though fantasy stories can just as easily take place in our modern world, or in a Post-apocalyptic society where technology was buried alongside the old world. These anime also tend to feature magic or other extraordinary abilities, strange or mysterious creatures, or humanoid races which coexist with humanity or inhabit their own lands removed from ours.
Mecha are self-propelling machines that are modeled after humans; some can change into multiple, non-humanoid formats as well. They're usually controlled by an internal pilot or by remote, but are sometimes sentient beings that move autonomously. A mecha's size ranges from bulky, wearable armor to a massive, towering contraption and beyond. While mecha have a wide range of applications, such as making manual labor easier, they are most commonly portrayed as heavily-armed war machines.