What have been the most transformational marketing innovations in society? TV and direct mail/database marketing rank up there. Email, the web and social media also do. And so does mobile — but why?

It is too easy to think of mobile as nothing more than a small screen. Web designers and developers work hard to ensure that their sites are responsive a Web design that automatically reformats itself for the desktop, tablet or cellphone screen. And then the effort stops.

Mobile is unique not because of the screen size, but because it keys into two critical marketing triggers: location and urgency. Yes, it is true that a flyer outside a retailer's shop meets these criteria, but the flyer is a one-way broadcast. There is no interaction, there is no user identification and there is no tracking. And because of this, there is no "big data" that can later be mined to encourage a later transaction.

While the possibilities for mobile marketing range from text to location-based emails to location-based social sharing to who-knows-what, there are several principles that are critical for mobile marketing using the Web, whether it is a mobile app or a mobile-responsive website:

1. Location: Because a user is only using the mobile when they are either looking for something or they have already arrived, the device needs to take this into account. Directions "from here," the local location's phone number, the currency, local spellings and local-only deals should be front-and-center.

2. Just in time: If someone is checking their smartphone, it is likely because they are in the midst of a specific customer journey. Yet once they leave the location, the likelihood of them transacting quickly diminishes. Time-bound deals and up-to-the-minute dynamic content are urgency triggers and a powerful call to action.

3. Simplicity: Most mobile sites have the exact content as the main site, but accessed through a revised navigational structure. It is far less likely that a user will use their smartphone to drill into the depths of your site to read several pages online. Strip away the less relevant, and give the user what they need up front: drive them to action. If the site is 80 percent less complex, you'll have that much more activity.

This week's action plan: Take a look at your website, but do it from your smartphone. Does it take into account your geographic location? The principle of "just in time"? Simplicity? If not, perhaps you should build a new mobile site into this year's marketing plan.