What makes email, Facebook, and Google so valuable? Answer: Visiting them is largely unprompted, notwithstanding the synapses that fire in your brain that make you check your email, your Facebook feed, or decide to research something on Google. In other words, people pull content themselves, rather than having that content be pushed — or foisted — upon them.

The best way of looking at consumer web applications is as a complex stack of “pulls” and “pushes.” Lest these terms be confused with an earlier generation of push: a “pull” is an unsolicited action by a consumer, whereas a “push” is a solicitation by a seller/producer.  The consumer ultimately “pulls” from a mobile phone or computer. Everything else is “pushed” to the consumer, through ads, e-mails or other marketing efforts from companies eager to get business and traffic.

The greatest trick that Facebook ever “pulled” was transforming itself from a push platform (dependent on email to woo users back) into a de facto pull platform.  Facebook touts that 50%+ of its users log-in every day, and my guess is that the vast majority do so with no prompting. Push is still valuable but simply complements the massive pull that Facebook has developed.

Why is Pull so essential for a web company? The intersecting forces of human psychology and economics.

First, psychology: consider how most people hate being “sold” to. “Being sold to” is a form of push. Consumers get hundreds of unsolicited offers and emails pushed to them every week. They learn to tune these solicitations out, especially if they are not in a buying mindset. Relevance is a function of offer-consumer fit paramaterized by time.

Second, economics: A pull platform doesn’t need to spend any money to reach or acquire customers; a push platform does. Facebook’s marketing spend per user has to be the lowest of any company known to man. Granted, Facebook is intrinsically viral and laden with network effects, but the unprompted pull phenomenon has been crucial to Facebook’s dominance.

The value of pull is not just for consumer companies. Any Business-to-Business company knows the value of “demand generation”: catalyzing a “pull” by customers. The quickest and cheapest sales cycles start with a pull by the prospective customer.

For any web company, fostering Pull is essential to creating value and engagement.  There is no shortage of great applications and amazing technologies which stagnate due to a lack of pull.  But the greatest economic achievement of being a “pull” platform is in becoming the mechanism by which “push” companies must engage with audiences, paying handsomely to do so. This expectation is why a company like Twitter can be valued in the billions with minimal revenue.

Here are some ways of thinking about fostering pull:

Plan Around Events

Groupon Now is Groupon’s attempt to add Pull to its traditionally Push service. I want to eat, where do I go? Groupon. Every human desire has a natural pull tendency. Being the “first responder” to a human desire is incredibly valuable.

Find Offline Analogies

Most forms of pull fit a predefined social pattern, per the comment on “human desire” above. Before Google, people used phone books (unprompted) to find services. Before email, people would check their postal mailbox, generally at a given time (after the mail was delivered).

Answer Recurring Questions

There are certain types of content that consumers will invariably pull (or want pushed to them). These types of content generally answer recurring questions of a consumer. How much did I spend Receipts, bank websites)?  Where am I going (Google Maps)?  How do I get there (Kayak)? What’s wrong with me (webMD)?

Build Brand and Familiarity

Once one of the above is satisfied, brand and credential storage foster pull. A frictionless and “known” experience catalyze pull for transactional activities. While Amazon, as the largest spender on Google, does a fair amount of push, they also benefit from a tremendous amount of pull when consumers decide to shop. This is a combination of the brand but also their accumulation of user/payment credentials.

There is no substitute for pull in establishing success for a web company; the key is producing something sufficiently valuable in repeat interactions. Reid Hoffman has notedthat “social networks do best when they tap into one of the seven deadly sins.” It’s no coincidence that people have, unprompted, “pulled” those sins since the dawn of humanity.