A platitude is a trite, meaningless, biased or prosaic statement that is presented as if it were significant and original. The word derives from plat, the French word for "flat". Whether any given statement is considered to have meaning or not is highly subjective, so platitude is often — but not always — used as a pejorative term to describe seemingly profound statements that a certain person views as unoriginal or shallow.
The statements most commonly described as "platitudes" are short proverbs and aphorisms which are intended to motivate or encourage another person, but which are in reality overly-simplistic or cliché; for example, "You will succeed if you try hard enough", a statement which ignores the simple fact that it is entirely possible to fail in spite of one's best efforts. Some people dismiss such statements entirely, arguing that since the statement does not properly represent reality any motivation or other emotion felt as a result of it must also be illusory. Others argue that the omitted facts of reality are ones that are not useful to consider—knowing that you may fail for reasons beyond your control does not make it less likely—so such statements may be valuable as a rhetorical tool, even if not technically correct.
Another common platitude is the conversational lubricant "How are you?", usually a rhetorical question, and its attendant responses, such as "I'm fine; how are you?" This exchange, occurring most often between strangers or in professional settings, is so ubiquitous in English-speaking social discourse that it has almost completely discarded its literal meaning or intention.