The internet has played an important role for those trying to find out what happened to friends and relatives caught up in the blasts in Mumbai.
The net provided help beyond that available on the ground
It has also been used to offer help and collate data on the dead, the injured and the missing - at a time when phone lines were often jammed.
And it has provided a platform for people caught in the blasts to post eyewitness accounts of their experiences and photos of the attacks.
A variety of news and personal websites have provided a forum for people in India to express their reactions and recount their experiences, says BBC world media correspondent Sebastian Usher.
The most important site for locating people is Mumbai Help - a blog set up last year during deadly floods - which now has more than 60 pages devoted to messages from people searching for information and advice.
Many come from people outside India who have been unable to contact their family members in Mumbai, asking for help from third parties inside India who might find it easier to contact them.
There are many messages from people saying thanks for the reassurance they have received that their relatives are safe.
Immediately after the blast, there were also tips on where to seek shelter, whether to stay put in the office, and what the situation was like on the roads.
Later, there were calls to donate blood and where to go to do so.
On photo sites like Flickr, graphic images of the scene of the bombings taken by ordinary people have been posted.
And blogs such as Ultrabrown and Sepia Mutiny give a blow-by-blow account of the events unfurling aboard the trains, and the immediate aftermath of the bombings.
They collate news reports, eyewitness accounts, reaction and comments, as well as offering forums for discussion for users.
On his blog, Dilip gives an account of his visit to Bandra station not long after the blast there.
"One train sits on the track north of Mahim station, long dark and silent. Perhaps it casts a shadow, because it is even darker as I walk past...What must it have been like here an hour ago, with bodies flying about and people running for their lives?" he asks.
He also gives an account of how people begin to rally round.
"Two young men press glasses of water into my hands...Please, help yourself, they say. And if you've got a long way to go, please come in and have some food before you walk on... It's not even two hours since the bombs went off, and these guys are already organised with food, water, tables and shelter."
Others are beginning to analyse what the blasts mean for India and the wider "war on terror".
One blogger turns his attention to Mumbai's railway network itself.
"The focus should be on infrastructure," Sunil Doshi says on Mumbai Train Blasts 2006, "so people can see each other in the trains...If trains are filled four times more than capacity, then people are bothered just to get in...WHO gets in nobody is interested in."
On India Uncut, Amit Varma says the nature of terrorism is changing.
"Soft targets in big cities are more and more likely to be targeted... this represents a challenge for Indian secularism that it must win if we are not to squander the gains of independence and democracy," he says.
There are also threads such as Pickled Politics, which use the Iraq war, Western foreign policy and international media coverage to discuss Tuesday's events and interpret them both inside and outside India.