It's fair to say ICS is a pretty life changing experience for most volunteers.
You've got the opportunity to work on projects that make a difference, challenge yourself to develop as a person, and meet a huge range of passionate people.
But for many volunteers, the bond with the people they meet on placement doesn't stop after their 12 weeks away.
From marriages after placement to friendships that transcended the language barrier, this World Friendship Day we've tracked down some of the most surprising, romantic or inspiring friendships to emerge out of ICS.
Four unlikely friendships
I married my best friend from ICS
For Hanna Ziwa, her ICS placement with Restless Development in Jinja, southern Uganda, brings back some happy memories.
That's because she shared it with husband Ramathan, who she currently lives with in Uganda.
"I met my husband on ICS. He lived in the nearby town to the village I was staying in."
Not content with a long distance relationship, Hanna made plans to return to where it all began: "I moved back to Uganda after ICS to live with him and now he has been granted a visa to move to the UK.
"ICS has changed our lives - literally!"
The friendship not based on talking
When UK volunteer Rutendo met Bangladeshi volunteer Sengmi after a 24 hour journey to her Tearfund placement in Birishiri, she thought the language barrier was too much.
"In the first week, we didn't speak a lot as her English was limited and my Bangla was non-existent."
But asking for Sengmi’s number was the best decision Rutendo made: "Through texting, Sengmi and I found our own language and we became close. We bonded through dancing, hugging, blowing kisses and in laughter.
"I learnt not all friendships are based on talking. Ours is one of a kind and a friendship I have never experienced before."
My roommate was a sister to me
When UK volunteer Keira Henderson arrived at her host home in Tolon, Ghana, volunteer Josephine Zon Funiamwin didn't expect her to be like a sister.
"Having a roommate who becomes your best friend and a sister was one of my best experiences."
Spending the 12 weeks of their International Service placement sharing details of their lives in the UK and Ghana, Keira would spent her mornings teaching Josephine Spanish.
"We're always late to arrive at the office together because our bikes magically seem to break down at the same time! We're made to collect water for being late, but doing it together makes it all fun."
'I didn't have many friends before ICS'
Nokwanda Khwela grew up in South Africa. With few friends she could trust, her Tearfund ICS placement in Kwazulu Natal, in the east of her home country, was a big leap of faith.
"I didn't have many friends before ICS. But then I met my lovely, humble host sister, Maskhe.
"Even at home I don't have a person whom I can share everything with like I did with Maskhe. We talked about everything as if we were the same age.
"One of the things she did which really touched my heart was when she chose to go with me to my doctor’s appointment. She left all her work just for me."