A lot of us practically live our lives on the Internet these days. You can use it for communication, entertainment, handling of finances and schedules, purchasing just about anything and a host of other purposes. It can aid you in anything you are doing, good or bad (including cheating). There are even sites that specifically cater to cheaters, like AshleyMadison.com, a dating site that allows you to hook up with willing affair participants.
But your forays onto the Web leave signs of what you have been doing for anyone with access to your computer to find. Before you go visiting dating sites, buying gifts or making hotel reservations on a computer in your house, know that your partner can easily sniff out sites you've been visiting. You might want to set your browser to not save your history if you plan to engage in any illicit activities.
Even if you delete your browser history, cookies may also be saved on your computer. These can reveal what sites you've visited and even allow someone else to log into your accounts if you've allowed sites to remember you. Other possible tell-tale signs of Internet activity are temporary files of downloaded Web content. Covering your tracks is never as simple as deleting your history, since a suspicious partner is likely to dig further.
Third parties can also exploit security loopholes to view your history and target ads at you, but that's probably last on your mind if you are engaging in an affair. Still, an odd collection of advertisements for things related to dating and relationships could potentially tip off a spouse, as well.