'I was there': Eyewitnesses recall how 2015 changed their lives
From the devastating gun attacks in Paris and Tunisia to the crippling earthquake in Nepal and the unprecedented migrant crisis in Europe, 2015 was a year in which human stories and experiences came to the fore.
People caught up in these events shared their experiences with the BBC through social media, chat apps and email.
Here, we revisit and hear from a number of them.
Mandy Palmucci, 33, from Chicago, US, survived the deadly shootings at La Belle Equipe bar in Paris, where 19 of the 130 killed in the 13 November attacks died.
"I was sitting outside La Belle Equipe with three friends when the attack happened.
"What we experienced was terrible. One of our group was shot in the leg. The rest of us were uninjured.
"We stayed with her and helped others there. We covered people and held IV drips - anything to help.
"I left Paris the day after it happened. I wanted to return for the memorial two week's later but couldn't travel then.
"At the table next to us, about 11 people were killed. I held on to a man who lost everyone.
"They were there for a birthday party [for waitress Houda Saadi, who was among those killed, along with sister Halima}.
"My heart is still broken from these events and I'm trying to get through this grieving process.
"I now count the Fridays. It's hard to distract me from 21:36 Paris time on a Friday, when the attack occurred.
"When I find myself enjoying something the guilt can be overwhelming. I've since got a tattoo with the motto from the Parisian coat of arms on my left ribs, which is roughly where I landed when we hit the ground during the shooting.
"It's been the only thing I've actually allowed myself to enjoy and now that my bruises are gone, I'm glad there is a visual reminder beyond the internal one I feel every day.
"I still have thoughts related to the attacks every three to four minutes, at least.
"The immediate victims around me are never far from my mind and I have been consumed with knowing how people who were there are doing now.
"The updates in the news have slowed, but I've managed to find out about one man who was sitting to my right, another who was to my left, the lady directly behind me and a group of gentlemen near us.
"The only ones I don't know about, who I can see so clearly in my memories, were the two directly on the other side of us inside of the bar. I don't think I'll ever know.
"I'd prefer to forget about Christmas this year, it's not really on my mind."
Debbie Horsfall, 23, from Huddersfield, UK witnessed the gun attack in Sousse, Tunisia, which killed 38 people in June.
"It was a terrifying experience, but I'm doing my best to deal with it and try to surround myself with people who help me get through it.
"I was talking about it so much at the time, that was almost therapeutic, in a way.
"Then when everything died down, it slowly started to sink in. It was difficult but I did my best to not let it become part of my life, where I refer to myself as 'the person in Tunisia'.
"If anything, it teaches you to not take things for granted. You change your opinion on little bickering things. You realise they're nothing.
"I travelled to Spain in August and went on the beach again, which I was really proud of. I know it sounds silly, but it was a really big thing getting back on a beach so soon afterwards.
"Since Tunisia, I do all the checks on the area I'm travelling to beforehand. It just seems that at the moment wherever you go, you've got to watch your step.
"Obviously, there will be certain times when things hit you. Every now and again I'll get little flashbacks. That's just something you've got to learn to deal with.
"I don't think it's anything that I'll ever get over but it's something that I've been through and I can't get rid of it.
"I'll be with my family at Christmas, so I've got the important people around me.
"I'll probably reflect on the fact that I'm still lucky enough to be here to celebrate and unfortunately others aren't."
Sajiya Gurung, 18, from Kathmandu, survived the devastating earthquakes in Nepal in April, which killed an estimated 9,000 people.
"The earthquake was terrifying. Some of my relatives and friends lost their lives and some of us survived.
"Most people could not go back to their homes after both earthquakes. There were many aftershocks and everything was moving around. Everyone had to stay outside.
"We had to sleep on the street for three nights. Even though we were outside, we were afraid that the houses would fall down on us.
"It was also very cold at night, we only had one or two blankets which we had to share.
"We couldn't even stay at a shelter because we thought it would fall down on us.
"Our house was OK, but many people from the affected areas are still living outside, hoping the government will pay for their damages.
"I am more afraid now. You worry all the time about windows or other parts of your house coming down on top of you and that you're going to die like that.
"There are now about two or three aftershocks a month.
"I will spend Christmas with my friends and family. I'm appreciative of life now because you don't know if you're going to die tomorrow."
Gassama is a Gambian migrant who travelled through Libya to Italy just over a year ago. He describes how he is coping and how he has dissuaded others from making the same perilous journey, which claimed the lives of more than 2,800 people.
"Life is still very difficult. I came here at the end of last year and I'm still in an immigrant centre about 31 miles (50km) outside Milan with 150 others.
"They are all mainly African, with six of us to a room.
"Some have moved on to Germany and Austria. They say life is better there but, like us, they still can't get documents to work.
"I have just sat the test to try to obtain work documents for the second time and I failed again.
"No Gambians have passed the test. We are now trying to consult a lawyer to help us obtain our documents.
"I get 75 euros (£54) a month welfare to live on. The food I live on is generally not good for us.
"I can't even leave, as I have to sign in and out every day and if I'm not back by 22:00 I won't be allowed back in. So there's no freedom of movement.
"There are so many problems here, but I've been through situations like this before in Libya - on my way here - so I'm used to it.
"Other African migrants have come here after making the journey this year, mainly Nigerians. They are too scared to talk.
"There are not many Gambians coming now, mainly because of people like me telling them not to, because it's too dangerous to travel through Libya and there is no work here.
"My Facebook group has also had an impact in persuading others not to come. They are more likely now to stay in Gambia or try to find work elsewhere in places like Senegal.
"Meanwhile, I'm still here, not working or doing anything. But who knows what tomorrow will bring.
"I don't celebrate Christmas, as I'm Muslim, but if there are others here celebrating, I will join them."