Why do people vote for a particular candidate in the election? What exactly influences their decision?
There are several factors that have the most significant impact. Often these are not political issues but voters' background, party identification and past performance of elected officials. Background refers to voters' social identity, like gender, race, religious preferences and socioeconomic status. Most voters tend to vote for candidates with whom they have the most in common. Speaking about party identification, people are inclined to vote for whichever party has influenced their childhoods. For instance, those brought up in a family of Republicans would more likely consider themselves politically conservative, and those raised in a family of Democrats oftentimes consider themselves liberal.
Usually people know how they are going to vote. It's rare indeed that they change their mind. But candidates do their best to manipulate voters' thinking. Each of them has a team that studies the general sentiment and creates a strategy for changing the public opinion in their favour. They try to talk about issues that make people emotional. When people get emotional, they don't listen to facts. Candidates use the tone of voice and repetition to draw attention to their message. When people hear something over and over again, they will soon start to believe it.
Let's look at Donald Trump for instance. What makes him so popular? He is a master of manipulation. He knows the secrets of a great orator and succesfully applies them in his speeches. His tone is very powerful, and he changes it depending on the situation. He speeds it up. He slows it down. His speech doesn't sound like a monotonous drone, but instead is rather conversational, which elicits trust from people. He always puts his arms on the podium during the speech to look solid, which adds to his trustworthiness on the subconscious level. Trump has got a message that resonates well with people. He has a strategy that his opponents don't have. He uses mass media in a way that other candidates have never been able to utilize.