So Facebook's Safety Check feature, which allows users to mark themselves as "safe", was well used in the aftermath of the attack in London at the weekend.
For some, it offers an instant way to get in touch with people around the world in just one click but for others it can make them feel as if they are "riding on the coat-tails" of a tragic situation.
Student Megan O'Hagan lives very close to Borough Market and London Bridge, and felt the safety check on Facebook was a very quick and easy way to let a large number of people know very quickly about her situation.
"I also find it useful to check on people I know in the area if I do not have their number or cannot contact them for whatever reason," she said, but also thought that it could be open to some misuse.
"Several of my friends from over two hours away marked themselves as safe but I think it should only be available to people that can confirm they are in the area, as no-one is wondering if someone who lives in Liverpool and hasn't been to London is safe in a terror attack in London!"
Italian psychologist Susanna Rota lives near London Bridge and was in the area when the attack happened. She also used Facebook to mark herself safe on Saturday but this was the first time she had decided to use it.
"Even though I lived in London for 17 years I didn't feel the need to use it previously because I wasn't directly involved and did not really link myself to what had happened," she said. "But this time it was the quickest way to let my family know I was safe.
"I remember during the 2005 bombings there was no such way to get in touch with people and there were problems with the phone lines too. It took a very long time to get in touch with my family in Italy."
Since the 7/7 London bombings, Ms Rota thinks that the growth of the internet and our use of Facebook has changed the way we view ourselves and others.
"It can be a very positive thing but it can also be negative. it depends on whether we need to let people know we are safe or want people to ask us because we want to grab attention," she added.
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Simon Beech says he did think about letting friends know on Facebook that he was safe but ultimately decided not to because "there was enough tragedy without me riding its coat-tails".
He said he knows that Facebook can enable people to be very kind to each other in times of severe turmoil with people offering taxi rides or accommodation to those caught up in the event.
However, he was also aware on Saturday that some people were taking the situation less seriously.
"Somebody was offering accommodation in China and one man seemed to be well-known for always offering assistance as if to further his reputation," said Mr Beech.
"One poor woman obviously felt that she needed to do something, but as she didn't live in London she offered a 'shoulder to cry on' which earned her a reasonable amount of scorn from other people," he added.
"It could just be teenagers trolling too, I suppose. But you open yourself to the misgivings of others."
The terrible loss of life and injury in the attack can not be overestimated but some Facebook users including Tariq Ahmed, chose not to mark themselves as safe because he felt it was magnifying the level of danger.
He said: "The threat of being killed in a car accident is much greater. Didn't want to contribute in he overexposure of the type of threat that is least likely to happen."
And for the same reason Amber Philipps said she marked herself safe but later questioned the decision adding: "...actually marking myself 'safe' is almost making people  feel that being caught up in the attack is extremely likely".
By Annie Flury, UGC and Social News
When news starts to break of an unfolding emergency it probably seems natural that most people want reassurance that their friends and family are not in danger.