The Department of Health is also planning a major advertising campaign early next year to tackle discrimination against people with mental health problems.

BBC: Bid to cut hospital suicides

The NRA is planning its own advertising campaign, but despite being one of the best-funded lobby groups in America its spending is unlikely, for the moment at least, to rival that of Mr Bloomberg, he adds.

BBC: Michael Bloomberg funds $12m US gun law campaign

To lure in even more users, Microsoft is planning on launching a massive advertising campaign, one that will include TV and radio spots (see one of them after the break), online ads and even posters in subway stations.

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