Abstract: A method comprises applying a first rule to a second action in an online environment to produce a result. The second action is caused (702) by a first user in response to a first action (700). The first action is one of a plurality of actions in the online environment to which the first user is exposed that precede the second action. The plurality of actions is caused by at least two users other than the first user. The method further comprises: identifying (706, 708) the first action from the plurality of actions; identifying (710) a second user from the at least two other users, based on the first action, wherein the second user caused the first action; determining (518) if an intervention action is to be taken against the second user.

Abstract: A plurality of rules are applied (500), for guarding of a first user, to a user action in an online environment to produce results. The rules relate to online user behaviour in the online environment. The user action is non-linguistic and non-textual to the first user. Each of the rules has a respective rule value associated with it. At least some of the rule values are different. Based on the results and the rule values associated with the applied rules, whether at least one intervention action is to be taken against a second user is determined (516). The intervention action, if any, may then be taken (518).

Abstract: A rule is applied to a user action in an online environment to produce a result. The user action is by a second user and a first user is subject to the user action, or the user action is by the first user in response to a prior action by the second user. Based on the result of the applying indicating to do so, a score is determined (502-514) based at least: a first value corresponding to the rule, and a second value based on past actions in the online environment between the first user and the second user using action information relating to the second user stored in an action log of the first user. It is then determined (516) if an intervention action against the second user is to be taken based at least on the score. The intervention action may then be taken (518).