Stalking is the intentional following of someone to control or harass the aforementioned individual as usually it's a jilted lover or a creepy person who's the stalker, but in rare cases bullies/gangs stalk someone that's usually a loner to harass/intimidate this outcast.
James was a gay former cop that was in love with a teenage boy named Kevin that wasn't interested in him, so James stalks/ follows Kevin in his White truck from Kevin's school because he's obsessed with him as this is intentional stalking. Ultra-liberal friends/gangs stalk a conservative loner to and from work for several years, because they believe he supports Donald Trump and because he called the cops to report them for assaulting/harassing him as this is deliberate stalking. Ultra-conservative reporters obsessed with AOC constantly stalk her or accost her out of hatred of her influence as this is obsessive stalking.