What is the principle of DDOS attacks?

Question

DDoS Protection

Such a question is ripe.
As everyone knows, DDoS attacks are made by overloading the victim's server. But let's say, for web pages, one type of attack is needed, for (for example) cs go servers, another type, and so on.
The question itself is: what kind of attack is needed, and how to implement it from the point of view of the code (at least explain abstractly)?
Do not think, it is necessary solely for educational purposes, since I am familiar with all the articles of the Criminal Code

Answer 1

DDOS can be obtained (and most easily implemented) by stupidly blocking the channel. It is also possible to generate queries that require much more resources to process than to create the query itself: full-text search, for example.