Several public institutions and private organizations from Lithuania were targeted by of a denial-of-service cyberattack, the Russian hacker group Killnet has claimed responsibility for it. A Distributed Denial of service (DDoS) is a type of  coordinated cyberattack designed to disrupt a network or even to disable it completely. Usually a special type of malware is being used to generate a massive  of traffic, with negative impact on the network functionality.
A frequent example of DDOS attack to a website is accessing it from numerous locations in the world, rendering it inaccesible to its visitors.