Many websites are aimed at children, and many that aren't aimed at children are used by them. Although not all website operators seek to enter into contractual relationships with users, many do; and there lies a problem. The general rule of English law is that individuals under 18 years of age - minors in the legal jargon - are not bound by any contracts that they may enter into. In some circumstances, even where the child is bound, such contracts are voidable at the option of the child.
The rationale for the general rule is that children should be protected from their own inexperience, and from others who might take advantage of that inexperience. Against this must be balanced the real risk that children will take advantage of honest adults who deal with them. There are a range of exceptions to the general rule of non-enforceability that seek a fair compromise.
Perhaps the best-known exception to the general rule that contracts don't bind children, and certainly the most relevant in the context of website-related contracts, is that contracts for "necessaries" are binding.
Necessary goods have been defined as those goods that are "fit to maintain the particular person in the state, station and degree ... in which he is" (Stocks v Wilson). Necessary goods might include food, medicines and clothing; while necessary services might include lodgings, educational or training services, and medical or legal advice.
Necessaries are to be contrasted with "mere luxuries". Many goods that might seem at first glance to be mere luxuries may be considered by the courts to be necessaries. In the jurisprudence, the classification of a good or services as necessary, or merely luxurious, often depends upon the particulars of the case.
Clearly some contracts entered into through a website will fall within the definition of necessaries; others won't. In many cases, it will be unclear whether the contract is enforceable against a minor as a contract for necessaries. Are social networking services necessary to any particular child? To some, it might be argued, they are.
There are a number of other exceptions to the general rule, but most of these are unlikely to be relevant in the case of contracts between users and website operators. For example, contracts for the exercise of a profession and contracts apprenticeship may bind a minor - but few if any website T&Cs govern the conduct of a profession or apprenticeship.
If the goods or services in question haven't yet been supplied to the child in question, there is a further doubt. There are arguments - although I won't go into them here - that children are only liable under contracts which have been performed by the supplier of goods or services. Accordingly, website operators should be aware that, even where they are contracting to supplying necessaries to a minor, there is a risk that until such time as the goods or services are supplied, the minor may escape contractual liability.
While the legal position is of some interest, after-the-fact it will usually be an irrelevance. Parents are not in general liable on their offspring's contracts, and children may have little or nothing in the way of assets. An action for damages against a child is most likely to damage the claimant - in more ways than one.
If a website operator wants to ensure that contracts with users are enforceable, the easiest way to do that is to take practical steps to ensure that children aren't able to sign-up.