A ban on tobacco displays is coming into force in England - with ministers promising it will help curb the number of young people taking up smoking.
Cigarettes and other products will have to be kept below the counter in large shops and supermarkets, while small outlets are exempt until 2015.
Other parts of the UK are planning similar action to drive down smoking rates.
Critics say the ban is discriminatory and will not discourage young smokers.
Health Secretary Andrew Lansley told the BBC he hoped the ban would prevent people from taking up smoking and also help those trying to give up.
He said: "Firstly, it reduces the visibility of tobacco and smoking to young people. And, of course two-thirds of smokers started smoking before they were eighteen.
"So, if we can, literally, arrive at a place where young people just don't think about smoking and they don't see tobacco and they don't see cigarettes - then I hope we can make a big difference."
He said the government recognised the pressures on retailers to comply with the ban but added: "We want to arrive at a place where we no longer see smoking as a normal part of life. We're doing it by stages with constant active pressure."
A fifth of adults smoke - a figure which has remained steady in recent years after decades of rapid falls.
A plan to force manufacturers to put cigarettes into plain packets is also expected to be put out to consultation later this year.
The display ban will apply to shops of more than 280 sq m (3,014 sq ft).
Public health minister Anne Milton cited evidence from Ireland which suggested the measure could play an important role in discouraging young people in particular from smoking.
"We cannot ignore the fact that young people are recruited into smoking by colourful, eye-catching, cigarette displays.
"Most adult smokers started smoking as teenagers and we need to stop this trend."
Jo Butcher, of the National Children's Bureau, agreed: "It's essential that we create a culture that promotes and protects public health and tobacco legislation is a significant factor in making this happen."
Jean King, of charity Cancer Research UK, said the ban would help stop children who are attracted to brightly coloured tobacco packaging from taking up smoking but further action was still needed.
"Of course we want to see the pack branding taken away as well. This is not a normal consumer product, it kills people. We want to protect the next generation of children," she said.
However, the move has upset the tobacco industry.
Moves by Scotland to introduce such a ban have been delayed by legal action taken by Imperial Tobacco.
Meanwhile, a spokesman for British American Tobacco said: "We do not believe that hiding products under the counter or behind curtains or screens will discourage people, including the young, from taking up smoking.
"There's no sound evidence to prove display bans are justified."
He added if anything it could encourage the illicit trade of tobacco products.
Andrew Opie, from the British Retail Consortium, said it was wrong to believe the legislation would have a major effect on young people and it was supermarkets and other shops which were bearing the brunt of the costs needed to comply with the ban.
He said the organisation had calculated that it cost more than £15m to ensure everything was sorted out before the ban came into place.
He said: "Children are more likely to smoke when they're in a household where parents smoke and also they tend to get their cigarettes from either parents, or older peers, not directly from supermarkets.
"It's certainly caused a lot of disruption to retailers as they didn't actually get that much notice to comply - and if you think that this is 6,000 shops in England, there are only so many shop-fitters that can do the work."
David Atherton from the pro-smoking Freedom to Choose pressure group told BBC Radio 5 live he believed the state should not interfere with people's personal habits and added: "The idea of the anti-smoker groups is to denormalise us and to turn us into social lepers."
The display ban was announced by the government last year as part of its tobacco control strategy.
Although the legislation allowing it to happen was actually put in place by the Labour government before it lost power in 2010.
A number of countries, including Canada, Ireland, Iceland and Finland, have already introduced similar bans.
Prof David Hammond from the University of Waterloo in Ontario, said the ban led to a decline in smoking - especially among the young - in Canada.
"The declines were greatest in the provinces where the ban had been implemented the longest. And that's consistent with the idea that when you remove something like marketing, it takes some time for the residual marketing to wear out."