This is a very vague term -- rather too broad and non-specific. Nevertheless, many books (used as communication textbooks) define the term. According to Wikipedia, 
Communication is defined as: a process of transferring information from one entity to another. At the same time, Communication is also defined as sign-mediated interactions between at least two agents which share a repertoire of signs and semiotic rules. Then again, it is defined as the imparting or interchange of thoughts, opinions, or information by speech, writing, or signs, as well. These three definitions differ from each other:
Communication is defined as: a process of transferring information from one entity to another. At the same time, Communication is also defined as sign-mediated interactions between at least two agents which share a repertoire of signs and semiotic rules. Then again, it is defined as the imparting or interchange of thoughts, opinions, or information by speech, writing, or signs, as well. These three definitions differ from each other:- A process of transferring information from one entity to another.
- It focuses on information transferring bewteen two parties.
- It doesn't not imply semiotic differences of the term -- information -- between the parties.
- A model like the below is suitable for this definition: information source (sender), message coding, transmitting through channel, message decoding, receiver and noise
- This definition acknowledges that studying communication is studying science.
- Sign-mediated interactions between at least two agents which share a repertoire of signs and semiotic rules.
- The imparting or interchange of thoughts, opinions, or information by speech, writing, or signs.
- These focuses on signs and semiotic, and share(ing) and rules.
- Semiotics = studying signs processes / signification and communication / and signs and symbols
- Sometimes semotics is equivalent to semantics. = meaning of the words exchanged between communication parties.