A Trojan is a type of Malware, wherein a malicious piece of software hides inside of a seemingly legit piece of software waiting to be run when you least expect it.
For example, one of the most common ones are calculator apps downloaded from the store. They seemingly are just calculators, and do in fact act as one; however, when you open and run the app they commonly do much more behind the scenes that you’ll never know about (such as steal your private data!). This is also common with fake browser updates.
