According to some studies, brand loyalty may begin as early as the age of two. At the age of three, before they can read, one out of five children is already making specific requests for brand-name products.
The categories that they are most able to name a top-three brand for are crisps/snacks (42 per cent) and soft drinks (29 per cent).
The categories in which they are least able to name a top-three brand are toiletries (4 per cent) and clothing (9 per cent).
By the time children reach the age of five, most already have a couple of years' experience of nursery school, and are accustomed to interacting with their peers and leading lives beyond the family.
Favourite brands: Barbie, Disney Princess (girls); Tom & Jerry, Bob the Builder, Spider-Man, Thomas the Tank Engine (boys); Shrek, The Incredibles, LeapPad (boys and girls).
Role models: Girls Aloud (girls); David Beckham (boys); parents and teachers (boys and girls).
Media diet: Younger kids are not far along the road to literacy. So they absorb most of their information from visual media - and television is king. Four-year-olds not yet at school may have full-time childcare such as nursery school or childminders. If it is the latter, or if they are at home with a parent during the working week, they'll probably watch some daytime children's TV.
CBeebies and Nick Jr are TV channel favourites, with Dora the Explorer, The Wiggles, Balamory and the Fimbles popular viewing choices.
Those already at school (schooling begins in the school year in which a child turns five) will be reading basic books regularly and developing language skills rapidly. They are likely to be proficient with a computer mouse, too.
Electronic books such as Leapfrog's LeapPad give learning an easy-to-use interactive appeal, while compelling stories and beautiful illustration have a timeless hold on parents and young children alike - such as the hugely successful The Gruffalo and Room on the Broom by Julia Donaldson.
At this age, magazines provide a "double" audience of parent and child: reading them tends to be a shared activity. PPA Children's Group research, published in February, has found that parents consider magazines to be educational for children, even when their content is entertainment-based.
By the time they have been at school for a few years, children are able to play quite complicated and involved games and have developed powerful imaginations. Dressing up and role-playing games are very important to them and they are also adept at using pester power in subtle ways. Carrick James Market Reseach's Child Track study has found they can call upon £6 to £7 a week in pocket money. Sweets and confectionery is the main area in which they spend their money.
From around the age of seven or eight, friends become a much more important influence in children's lives, as they take their first tentative steps away from parental control.
Kids in this age group zap between channels during TV ad breaks, particularly to watch "grabs" of other programmes they like, MindShare's Play research found. Their attitude to advertising is ambivalent, but well-targeted ads can trigger strong product desirability.
Favourite brands: PlayStation 2, Power Rangers, Transformers, Spider-Man, Pokemon, Star Wars (boys); That's So Raven, Roald Dahl, Angelina Ballerina (girls); Harry Potter, The Simpsons, Cadbury's, Coca-Cola, Lego (boys and girls).
Role models: McFly, Kylie, Holly Willoughby, Girls Aloud (girls); Wayne Rooney (boys); Dick and Dom (boys and girls).
Media diet: Watch TV in the mornings before school, and in the afternoons when they come home. Their viewing comes from the wide choice of children's channels - Cartoon Network, CBBC, Nickelodeon, Jetix, Disney and Boomerang.
More than half also sometimes watch after the 9pm watershed, especially at weekends. This is the first truly multichannel generation, and they grow up with the internet as part of their everyday life. In spite of the growth of TV resources available to them, they are watching less television than before - around 2.3 hours each day, according to Childwise. Scooby Doo, SpongeBob Squarepants, The Fairly OddParents and Tracy Beaker are among their favourite shows.
The internet and magazines are important sources of information, as are the toys and game shops they visit. Half of this age group are already regular internet users. Two-thirds have a CD player, and one in six has an MP3 player. One in four buy their own magazines, with the Beano making a comeback among boys and Top of the Pops and Girl Talk popular with girls.
This is the transitional generation, popularly referred to as "tweens". This group is moving from a family-centred lifestyle to one focused on their peers. Children experience a major shift at the age of 11, when they move to secondary school and suddenly find they have far more personal freedom, spending power and peer-group influence.
"Collective individualism" is a big trend, the agency Propaganda believes.
The success of ringtones, phone covers and the like is driven by kids' herd mentality. They all want to conform and be accepted but, within the security of their own group, they want to express their individuality.
The success of the execrable Crazy Frog and other ringtone advertising has made mobile phones hugely desirable to this age band - the average age for children to have their first mobile phone has come down to eight.
Celebrity endorsement works particularly well with tweens, Egmont Magazines reveals. This is particularly true for the boys, who admire and support footballers, rugby players and cricketers.
Favourite brands: Nike, Adidas (boys and girls); PlayStation 2/PSP, Umbro, Yu-Gi-Oh, WWE, Batman (boys); Claire's Accessories, New Look, Hello Kitty, Bratz (girls).
Role models: JK Rowling, Sugababes, Lizzie McGuire, Lindsay Lohan, Rachel Stevens (girls); Green Day (girls and boys); David Beckham, national football team (boys).
Media diet: TV viewing for this age group is declining, with competition from the internet now significant. They watch TV for about 2.3 hours a day. Almost all have access to multichannel TV, and two-thirds have digital TV. Favourite channels range from children's - (CBBC Channel, Nickelodeon and Cartoon Network) to music (The Hits, Smash Hits TV!) and sport, in particular Sky Sports.
Two-thirds watch TV in the mornings, and four in five watch after school, though only a minority do so regularly. Half watch regularly after 9pm at weekends. Soaps, reality TV and talent shows are popular, while more offensive fare such as Little Britain appeals for its catchphrases and off-colour themes.
More than four out of five have their own TV, three-quarters have a DVD player, and slightly fewer have a video recorder. More than nine in ten have a CD player, one-third have an MP3 player - with developments such as the iPod Shuffle making MP3 players more affordable to the mass market - and two-thirds have their own radio. They spend more than an hour a day listening to music.
This savvy demographic is much more aware of what is cool within their peer group and distrusts the hard sell from advertisers. While 30 per cent of 11-year-olds admit they like to buy things they have seen in TV ads, only 20 per cent of 14-year-olds feel the same way (BMRB research).
At this age, children struggle against domineering parents, but also still cling to the parental safety blanket.
Pocket money of as much as £30 a week gives the older end of this bracket considerable buying clout, with clothes followed by mobile phones and music their top categories of expenditure.
More than nine out of ten have their own mobile phone, and the majority pay for this themselves. Many now use their phone for taking photos and videos.
Most buy sweets, drinks and crisps but are wary of food ads - especially those which claim that products are good for you. One in six of this age group have their own fridge.
Favourite brands: Nike, Adidas, Reebok, Calvin Klein, Motorola, Myspace.com (boys and girls); fcuk, Top Shop (girls); Lynx (boys).
Role models: The Killers, Coldplay (boys and girls), Jennifer Aniston (girls); Eminem, 50 Cent, Andrew Flintoff, Jonny Wilkinson, David Beckham (boys).
Media diet: Top magazine titles for boys of this age are: Match, PlayStation, FHM, Top Gear, Max Power and Nuts. For girls, Bliss, Sugar, OK!, Heat, Closer and Glamour. Only a minority often read books for pleasure.
This group watches an average of three hours of TV a day. Their favourites are music channels, sport, soaps and comedy, but they still watch some child/teen channels. Half watch TV in the mornings and two-thirds do so in the afternoons. But they are more likely to be watching after 9pm.
Nine in ten have their own TV set, four in five a DVD player. EastEnders, The Simpsons, Friends, Lost, Hollyoaks, My Wife and Kids, Match of the Day, Little Britain, Coronation Street, Will and Grace, Charmed and The OC are among the favourite TV programmes.
Three-quarters buy music and more than half download, with many doing so regularly. Most have a computer at home, and half have their own PC or laptop. Almost nine in ten are connected to the internet at home, half via broadband. Almost all access the internet, with half doing so daily, for homework, MSN, e-mail, games, downloading music and information. One in three go online in their own room, and one in five has their own website.
The majority have visited eBay and more than one-third have sold items there.