Unreal Engine provides a modular, visual, and layered animation system that scales all the way from small indie teams to multimillion dollar super productions.
Skeletal Meshes which hold geometry and skinning information.
Skeletal Meshes are imported from skin polygon geometry and also support morph targets.
Skeleton
You can merge similar skeletons as long as they only differ in terminal bone chains. For example, characters with ponytail or backpack bones can merge with a plain human model. Unreal Engine will ignore any unused terminal bones. You can also create modular character meshes with this approach. Just remember to export the full skeleton even if some of the bones have no influence over the mesh.
Skeletal Mesh
Skeletal Mesh Assets hold the geometry and deformation data for a 3D model. You can think of them as the skin that is drawn on top of the bone hierarchy. You can have multiple Skeletal Meshes associated with the same skeleton asset. They hold a lot of the same information that a Static Mesh does, including Materials and Level of Detail.
Physics Assets
Physics Assets provide ragdoll simulation and Simplified Collision. These can be built automatically by Unreal Engine, and you can fine tune each Collision Primitive size and range of motion. You can attach Physical Materials to each primitive and use the linked bone names as Tags to create gameplay relevant sections like armor or weak points
Cloth Simulation
Skeletal Meshes support cloth simulation. You can paint cloth weights directly in the editor to preview their effects in real time. You can reuse cloth simulation settings through a separate asset.
LODs are much more powerful compared to Static Meshes. On top of decimating its geometry, LODs can cull bones from the skeleton to reduce their overhead. This can be especially useful for hands. LODs can also simplify Materials and disable features, such as cloth or physics.
Animations Sequence
Animations Sequence Assets hold the key frame data to pose a Skeletal Mesh over time. These include bone transforms, but you can also add tracks to control morph target, Material, and custom attribute curves. You can extract single frame sequences from an animation. These are known as pose assets.
Sequences have some important configuration properties. You can adjust the rate scale to speed up or slow down your animation without the need to re-import. Compression can bring down the memory footprint of a sequence by discarding key frame data. You can control this through a variety of codecs.
Normally, motion from Animation Sequences will not affect the actor. Even if a sequence shows the character jumping, the actor’s actual location won’t change. Root Motion lets you feed changes over the location or rotation of a Skeletal Mesh’s root bone back to its owning actor. It can be very useful for action animations such as lunges and hit reactions. Keep in mind that it has performance and networking implications that you should consider before using it.
You can modify a sequence on the spot through Additive Animation Tracks. These curves will apply enough set over a specific bone.
Montages are the best means of playing animation from gameplay logic. They support network replication for multiplayer games and a special type of montage notify that can be handled directly from the Blueprint node.