Social network sites are places where people create their own profiles and can link up with anyone else who has a profile. The largest is Facebook, but there are many others including Twitter, Tumblr, LinkedIn, Snapchat and Reddit. You might even consider YouTube to be a social network site among content creators.

It’s common for people to link up with others, including former partners on social network sites. Often, social network sites will encourage this by recommending people who share mutual friends. As such, it’s not accurate to say that if people are friends on a site they are definitely engaged in infidelity. See our ‘friends on Facebook – can it be cheating?’ page for more information.

Sites nowadays use “smart filters” - or algorithms - that sort content. For example, if a client is liking photos of their ex, then Facebook will show them more photos of their ex. If a client watches videos made by their ex, this will lead to YouTube showing them more videos by their ex. A client might feign innocence by suggesting that this is what Facebook (or YouTube, etc.) is giving them but this is only partially true. These sites react to signals from the user.

If a client’s partner has a grievance about seeing content from an ex, or concern about such content, it may be reasonable to take steps to reduce this such as by minimising or hiding content. Blocking a person is also possible, but there may be practical reasons why this isn’t an option. In these cases, there are other options to explore such as placing a person on a “limited profile” on Facebook, unsubscribing from their content, or simply ignoring it.

Social network sites may also include messaging features. These messages can often be sent and received privately and sometimes they even expire. It’s important to remember that some partners may perceive ‘private messaging’ as a form of internet infidelity. See ‘messaging my ex – can it be cheating?’ for more information.

The presence of dating apps on a person’s phone, or registration for an online dating website in an email, is a strong indication that there is discord in the relationship. Dating apps sometimes frame themselves as enabling people to meet ‘friends’. This can form a sort of plausible deniability as one might indicate that they are on a dating app to make friends. Not only is this uncommon, it’s rarely the sole purpose of dating apps, especially if the client is trying to hide the application from a partner.

In general, where there’s smoke, there’s fire with dating apps. If nothing else, they’re evidence of one partner being inconsiderate of the other as the mere presence of a dating app can undermine feelings of commitment, unless of course the partners have discussed this between themselves. See our ‘how can we talk about what is OK online’ page for more information.

Chat programs range from benign interest groups to the raunchiest sex chats and everything in between. Chat programs can either be in a web browser (such as cam4 and chaturbate, which are popular adult-oriented webcam chat programs) or standalone software which can be installed on computers, such as Internet Relay Chat.

Chatting online can be especially intoxicating for people as the lack of cues makes it easier for the person to project more of their own fantasy into the chat, a phenomenon known as “the hyperpersonal model”. That is, that the reality of the person on the other side of the screen is less important than the fantasy that they play.

Chatting online is a behaviour where partners in a relationship might disagree over the importance of such an act. As it is ‘just chatting’ or ‘just fantasy’, a user might seek to minimise the significance of the action. For the someone else in the relationship, however, this behaviour could be very upsetting. It’s important then for each person to understand how the other is feeling.

People can and do meet partners (including extramarital partners) in gaming sites and virtual worlds. In some ways these work like sexting in that chat can be very explicit. However, there is the added complication that one might be embedded in an entirely separate social network. Gaming can be an ‘alibi’ as much as actually a pastime.

Online message boards allow people to post their own content and reply to other people’s. Many provide support forums or a place to discuss medical issues or hobbies. Because message boards are asynchronous, they do not afford the same level of intimacy as other forms of chatting that happen in real time (or near real time). Instead, people are likely to use message boards to learn new information and share resources, whether it’s advice or erotic content.

Some people have uncommon fetishes where it can be hard to locate peers through ‘normal’ websites. Particularly in the case of socially stigmatised practices such as paedophilia, zoophilia (sexual fixation on non-human animals), extreme fetishism, and adult baby play, which can push people to the ‘dark web’. These are websites that are generally anonymous even to the government or internet providers. To access these websites, one typically uses a special browser called ‘Tor’. Whilst Tor is not solely for such activities, there is a limited range of legitimate practices that commonly occur on Tor, such as sharing computer code, whistleblowing and remaining anonymous whilst browsing. As such, while the use of Tor in itself is not an issue, one might want to probe if a client is guarded about their use of Tor.