Developers regularly fix vulnerabilities in the operating system, software, and so on. They are responsible for ensuring that their product is safe. Therefore, the application of these changes (installation of updates, patches) made by developers is an important stage in IT security.
The firewall serves to protect against external intrusions, it blocks unused connections, and protects the software at the application level.
For the failure of the entire system, DDos attacks are applied. A huge number of requests are sent to the site. To process them, you need a huge amount of server resources. The system refuses when processing of all server resource requests becomes insufficient.
Encryption is the processing of data in such a way that even if an attacker receives data, they will not be readable for him.
VPN is often used to organize remote work with the office network. Through the use of VPN employees can get secure access to their computers from home.
Protect yourself from garbage on the mail with anti-spam tuning. And with the configured DKIM (digital signature for the letter) and SPF (the settings of the sender's domain), your letters will not fall into the recipient SPAM.