When I tell people I write about sustainability I often get blank stares. Some people will pretend to know what that means, and others will blurt out the question: what IS that?

I tried asking people what the word "sustainability" conjured up in their minds.
"A California thing," I got. "You turn off the lights, shop with recycled bags."

That's only part of it.

Large companies today, like celebrities and political candidates, get scrutinized on everything they do. You know the scandals: that product was made using child labor; those are blood diamonds; that company pays its workers below subsistence level; this company had an oil spill. Companies have to be not only compliant with the law, they have to be good citizens too. Their reputations matter. They can't be perceived to be greedy or corrupt or polluters of the environment. Consumers will boycott their products; investors will boycott their stock.

So companies have caught onto something known as "corporate social responsibility," or CSR. Some companies have a CSR officer, or maybe a director of corporate citizenship. But at some point, these social and reputational issues merged with the larger question of growth that is sustainable over a long time period, a question fraught with environmental and governance aspects. Investors started asking about "ESG," environmental. social and governance issues. And companies appointed sustainability directors to make sure all aspects of their operations were on board with new, forward-looking, best practices.

Lately, as inter-governmental organizations like the UN tackle big issues like global warming, corporations have taken sustainability yet another step forward by helping to lead the discussion and the search for solutions. Companies cooperate in efforts to wipe out corruption and violence in certain areas, using their economic clout. Some are voluntarily cutting carbon emissions and water use. Above all, there is a growing awareness that companies MUST lead us into a more sustainable future, because no one else will.

So how do we define sustainability?

Tobias Webb, founder of Innovation Forum, a London-based sustainability events and publishing business, notes that people think of social issues when they hear "CSR," and environmental issues when they hear "sustainability." But in fact social and environmental issues are inter-related. "Deforestation is a great example," he writes. "It looks like an environmental challenge yet many of the solutions are socially related (governance, corruption, institutions, sustainable livelihoods and regulatory enforcement)."

The World Business Council for Sustainable Development says this on its website:

"The starting point for the WBCSD's work is based on the fundamental belief that a coherent Corporate Social Responsibility (CSR) strategy, based on sound ethics and core values, offers clear business benefits. Sustainable development rests on three fundamental pillars: economic growth, ecological balance, and social progress.

"As an engine for social progress, CSR helps companies live up to their responsibilities as global citizens and local neighbors in a fast-changing world. And acting in a socially responsible manner is more than just an ethical duty for a company, but is something that actually has a bottom line pay-off.

"The WBCSD's basic message has always been very simple: business is not divorced from the rest of society. The two are interdependent and it must be ensured, through mutual understanding and responsible behavior, that business's role in building a better future is recognized and encouraged by society."

I couldn't have said it better. Meanwhile, I'll make sure to turn off the lights and recycle my shopping bags--and I hope you will, too.