In this increasingly globalied world, every nation, institution, group of human beings, and individuals are concerned with relationship with other human beings unless you live alone in the high Himalayas or deep in the amazonia forest isolated from other human beings. As the saying goes :you want to "put you best foot forward" - i.e. present yourself in the best light possible. Thus, you establish a good website for people to visit, or prepare a brochure described the good work you or your institution does. This is the "PULL" strategy. You try to pull in the audience. But initiative still depends on others. They have to DECIDE to visit you and consume the information you present. In a sense, it is still a passice strategy. On the other hand, if for example you are a research scholar, at least in the West, you are encourage to send out your latest new reseaqrch results/papers to a network of your acquaintences who are generally interested in your expertise and new findings. This is a more active "PUSH" strategy. It is "put you best foot forward and ask people to look at it". Of course, the distinction between pull and push is not absolute. There are other actions which lie in between. For example, insitutional advertising is not conerned with selling a product but a more active form of pull strategy. And having friendly reporter to publish favorable articles in their newespaper about your group is another active pull  strategy. Research scholar giving well prepared plenary lectures again mixes pull and push. Varieties are endless. The point is PUBLIC RELATION is important and worthy of care in our daily living. Everyone should practice good PR.