the gradual loss of intensity of a signal over it's medium's length in a glass fiber used for signals, imperfections and impurities in the glass diminish the signal's strength see: dispersion and/or bend loss
The available range of frequencies within a communications band, and the total capacity of information able to be transferred per unit of time. So when we talk about speeds up to 100Gb/s, we're talking bandwidth. A whole lot of it.
The attenuation which occurs as a result of the macroscopic bends in a fiber optic cable (e.g., as the cable rounds a corner or snakes upwards along a column inside an office wall).
Pink Floyd's Dark Side of the Moon album cover? That's dispersion in action.
Because of the properties of total internal refraction inherent in fiber optic cables, fiber signals experience virtually zero interference. Interference heavily impacts signals carried by traditional wires, e.g. copper cables, which are not self-contained and so greater care (and cost) must be taken to mitigate the fact.
The motion of a wave in/through space. If you toss a rock into the middle of a swimming pool, the waves on the surface of the water will propagate from the point of the rock's impact out towards the edges of the pool. Surf's up!
Just so, the rolling of a ball along level ground is a superposition, of the sum total result, of two separate motions: it's rotation (the ball spinning about its center axis), and its displacement (how far it travels along the ground from A to B). See interference.