Critical Thinking is the process of using reasoning to discern what is true, and what is false, in the phrases and "sound bytes" we hear everyday.
Part of it involves being familiar with logic and logical fallacies - those bits of false reasoning that are used to manipulate and mislead us.
Part involves being able to separate facts from opinions.
Part involves being fair and open minded; not dismissing anything without examination, and not accepting anything without examination, either.
Part of it involves asking questions, of yourself and of others, because that is how we uncover the truth, and the motivations behind the arguments.
Part involves self-regulation; the ongoing process of making sure that you have not fallen into any of the logical fallacies or rationalizations yourself.
Ideal critical thinkers are open minded; ready and eager to explore all ideas and all points of view, including those alien or opposed to their own.
They are not threatened by opposing views, because they are looking for the truth; they know that if they have it already, it will stand any scrutiny. And if they don't have it, they are willing to drop the falsehoods they have, and embrace it.
Critical thinkers question everything; using their tools to ferret out the truth, wherever it may hide.
The tools they use are Logic, Research, and Experience.
Critical thinking can not only make you manipulation proof, it can open new vistas for you, as things previously hidden become clear.