The people who contribute to Wikipedia — and I have — usually do a decent job of conveying basic information and providing reputable sources, but look at what passed the smell test for the thesis sentence of the Marketing Communications page:
The communication process is sender-encoding-transmission device-decoding-receiver, which is part of any advertising or marketing program.
Huh? Somebody has been reading too many scholarly articles about the simple — but not easy — job of marketing communications. I’ll say it again: know your audience, develop your message, use appropriate media, see what works and what doesn’t. Repeat.