The reports initially came in around 8 a.m. Thursday when Twitter officials posted on the site's official blog that a hacker brought down the site in a denial of service attack
"On this otherwise happy Thursday morning, Twitter is the target of a denial of service attack," the blog read. "Attacks such as this are malicious efforts orchestrated to disrupt and make unavailable services such as online banks, credit card payment gateways, and in this case, Twitter for intended customers or users. We are defending against this attack now and will continue to update our status blog as we continue to defend and later investigate."
A denial of service (DoS) attack comes from either one system or many, in which case it's called a distributed denial of service attack (DDoS). In either case, Twitter's description holds: A hacker hits a website with a deluge of activity or requests that renders the website inoperative.
As of 10:30 a.m., Twitter was functioning again, though another social-networking giant is also experiencing problems: Facebook. The MySpace-killer is still up and running, through the site is runing very slow and is someitmes unresponsive.
Also affected this morning is the popular blogging social network LiveJournal.
The source of these attacks remains uncertain, as does the connection to Facebook and LiveJournal. In the meantime, Twitter officials posted on their status blog that the attack is "ongoing" and that they're continuing to defend against it.
According to Twitter officials, the site will continue to run slowly, and external website and applications that make use of Twitter's API will work intermittently.