This question already has an answer here:
In this question, I am speaking mostly about the first time Voldemort calls them after being reconstituted at the end of Goblet of Fire. Here, there is no indication that they had been informed that Voldemort would be at the graveyard in advance (indeed, no one knew that he was back in Britain save for Peter Pettigrew and Barty Crouch Jr).
We know that Death Eaters can be contacted by Voldemort through the Dark Mark tattoo on their arms. Once they feel the 'call', they are to Disapparate and Apparate immediately to him. But since they need to know the 'destination' (one of the "Three D's" of Apparition), how are they able reach him without knowing the location of where he was?
Is there an explanation for this related to the Dark Mark 'tattoo contact spell' (my ineloquent term for it)? Is there some other power alluded to elsewhere in the series?
I think the question matters, because if they were able to find and reach Voldemort through Apparition, without precise knowledge of the location/destination (i.e. exactly where Voldemort is), why couldn't the Death Eaters do the same when trying to find Harry (or anyone), especially in Deathly Hallows, when Harry was over 17 and away from Hogwarts and other forms of protection? And conversely, why couldn't the Ministry, Aurors, members of the Order of the Phoenix or anyone Apparate to find Voldemort and capture him?