How expansive the internet is and with the addition of cloud services

Given how expansive the internet is and with the addition of cloud services, is the use of DDOS and DOS attacks still relevant?
What is a DoS or DDoS attack? What is involved in such attacks? Include a diagram.
DDoS and DoS attacks aren't designed to directly obtain information, but as a result of such attack, what information or "other benefits" might be obtained inadvertently? List and explain 4
What are the different types of mitigation strategies for both on-prem and cloud-based company assets?