  Semantic communication, regarded as the breakthrough beyond the Shannon
paradigm, aims at the successful transmission of semantic information conveyed
by the source rather than the accurate reception of each single symbol or bit
regardless of its meaning. This article provides an overview on semantic
communications. After a brief review of Shannon information theory, we discuss
semantic communications with theory, framework, and system design enabled by
deep learning. Different from the symbol/bit error rate used for measuring
conventional communication systems, performance metrics for semantic
communications are also discussed. The article concludes with several open
questions in semantic communications.
