VPNs

A VPN builds an encrypted tunnel between your device and somewhere else, and then your traffic carries on from there.

That is genuinely useful and considerably narrower than the advertising suggests. It protects the journey to the far end. It does not make a malicious website safe, does not stop malware, does not stop you being tracked once you have logged into something, and does not make an infected device clean. For a company it also does something specific and often overlooked: it usually puts a device onto the internal network, which is a large grant of trust to a laptop you cannot see.