In this paper, existing results regarding the fundamental limits of simultaneous energy and information transmission in wireless networks are reviewed. In point-to-point channels, the fundamental limits on the information rate given a minimum energy rate constraint are fully characterized by the notion of information-energy capacity function introduced by Varshney in 2008. In a centralized multiuser channel, the fundamental limits on the information rates given a minimum energy rate constraint are described by the notion of information-energy capacity region. Alternatively, in a decentralized multiuser channel, these fundamental limits are described by the information-energy Nash region. All these fundamental limits reveal the intrinsic trade-off between the conflicting tasks of information and energy transmission.