Tech Support Scams are programs, web sites, or unsolicited phone calls that try to scare you into calling a remote tech support number. These scams use scare tactics such as falsely stating that your computer has a virus, that they work for Microsoft or Google and that they have detected malicious network activity. These scammers will ask you to install remote access software such as TeamViewer, Logmein, or GoToAssist so that they can access you computer remotely. In some cases, they will install malware or other malicious software in order to make it look like there is a serious problem on your computer.
Source: https://www.bleepingcomputer.com/virus-removal/threat/tech-support-scams/