According to Kevin Mitnick renowned former hacker, in 2017 a strong (complex) password should consist of at least 25 characters or more - Art of Invisibility https://www.amazon.com/Art-Invisibility-Worlds-Teaches-Brother/dp/0316380504
In 2017 most us understand that a password alone is not enough we need to incorporate 2FA (Two Factor Authentication) into our password strategy and this is where this is where Yubikey comes in.
What is Yubikey and why do I need it?
"The YubiKey is a hardware authentication device manufactured by Yubico that supports one-time passwords, public key encryption and authentication, and the Universal 2nd Factor (U2F) protocol developed by the FIDO Alliance (FIDO U2F). It allows users to securely log into their accounts by emitting one-time passwords or using a FIDO-based public/private key pair generated by the device. YubiKey also allows for storing static passwords for use at sites that do not support one-time passwords. Facebook uses YubiKey for employee credentials, and Google supports it for both employees and users. Some password managers support YubiKey". - https://en.wikipedia.org/wiki/YubiKey
Yubikey vid - https://www.youtube.com/channel/UCqkvjt06Q4hejDEo5PZt6zg
Yubikey is compatible with good password managers such as Password Safe by Security Guru Bruce Schneier - https://pwsafe.org/
Yubico official page - https://www.yubico.com/
Discover Yubikeys - https://www.yubico.com/products/yubikey-hardware/