On the internet, push technology refers to data transactions initiated by the publisher, while pull technology means that data is being requested by the client. Of course, the systems per se must be requested by the client in any case. Pushing data on the internet doesn't mean pushing it on you.
Considering information in general, however, push and pull take on literal meaning: You can look up stuff yourself (books, internet), but information can also be forced on you (outdoor advertising, phone sales, etc). These are extremes of a continuum, though. The typical situation is something in between: submerging ourselves (more or less consciously, more or less voluntarily) in a flow of information – from TV, radio, newspapers – we focus on what interesting bits we see drifting by.
Information should be pulled. Looking things up ourselves makes us more conscious, more critical. We may automate this process, using feeds and aggregators on the internet, but even then we make our own selections, and we can easily customize them as we go along. We never forget that we're choosing from a large number of different sources.
Reading newspapers means that someone else has made these selections for us. Sure, we still choose between articles and different newspapers. But it's all profiled news. It's all been filtered and put together according to editorial directions, ideology and market analysis. Newspapers are ready-made dishes, sometimes already chewed, and – consequently – much too easy to swallow. The newspapers are probably dying now, and that's not necessarily a bad thing.
The principles of push and pull can be generalized even further, into trade of goods and services. Transactions are usually initiated by the customer. Pulled. Sometimes an offer has been presented in advance, or some information on assortment, but the customer still takes initiative.
Advertising is a different matter. Being manipulation more than information, it's usually pushed, often rather aggressively (TV, radio), or it's smuggled in among other information (newspapers, magazines, internet).
Finally, push/pull has some bearing on responsibility. While the sender/publisher is responsible for contents (quality, truthfulness, legality), responsibility for reactions follows initiative. If I scream at your face, I'm to blame if you get upset. When you read something in the newspapers or on the internet, however, it's at your own risk.
In the general sense, I consider pulling as something of a moral imperative: The initiative should come from the reciever; choices should be made consciously and without interference.
Even when someone needs help, this should, as a rule, be asked for. That's not to say it shouldn't be offered. In order to ask for it, one must know where to turn. But unless a person is unconscious or clearly irrational: Always take no for an answer. Don't push.