Research associate Melissa Low started a book swop event five years ago not to relieve herself of books she no longer wanted, but to regain her favourite titles.

After repeatedly lending beloved books to a friend without getting them back, Ms Low, 29, organised a book swop within a circle of her friends in order to get her prized possessions back without putting her forgetful friend on the spot.

What began as a cosy 12-person gathering at her home in 2011 has evolved into Books & Beer - a travelling book swop held every two months at different bars, sometimes drawing as many as 200 book lovers each time.

The event's rules are simple: Bring up to 10 books with you, get them stamped and then start swopping.

"You take home a book you wouldn't normally purchase, but someone's junk is another man's treasure," says Ms Low.

Apart from the drinks you may order for yourself, everything else is free of charge.

The next two meets will be held tomorrow and next Saturday in collaboration with National Library Board for its annual Read! Fest. These two editions of Books & Beer, to be held in Prinsep Street and Seah Street, will be renamed Books & Brew to include those who may not drink alcohol.

After the first swop, Ms Low enlisted the help of a friend, Ms Eileen Lee, 28, a manager at the Singapore Business Federation.

As the pair met as youth delegates at the 2009 UN Climate Conference in Copenhagen, Books & Beer naturally has green aims.

Ms Lee says: "It started out as a green movement to encourage people to recycle and share instead of buying and it's a cool way of meeting new people."

The two of them have since organised 36 swops and each event now sees a steady base of 60 to 80 book lovers. Books that are not taken are kept in their homes, where they have about 400 books in total.

Mr Andrew Pang, 31, a regular at Books & Beer. He says: "I initially only went for the beer. But then I found interesting books that I wanted to read and that it was a good way to network."

He has also hosted an instalment of Books & Beer at The Belljar, a bar in Canal Road, which he owns.

Ms Low says: "Sometimes, we choose the hippest new place in town. Sometimes, they're friends' recommendations and other times it's the bars that contact us.

"We've been turned down by only one establishment so far because we couldn't meet their guaranteed spend - we're a not-for-profit, after all. But most of the time, these places are very understanding and happy to host us."

For some book-swoppers, the fun may also lie in the mystery of it all. According to Ms Low, people have received signed copies of books and souvenirs such as photographs, train tickets or even love notes slotted in between pages.

For a heightened element of mystery, try this weekend's book swop at Togetherly Market - here, books are wrapped and only a cryptic note from their previous owners hint at the contents.

To participate, take a book, have it wrapped there, write a note and then swop it for another wrapped one from a shelf.

"You're supposed to write a note about what the book means to you or why the book was received or given away. Some even draw pictures," says Ms Germaine Leow, 31, who founded the arts and lifestyle market with Ms Cheryl Khong, 36, and Ms Wendy Ng, 38.

"There were already these little book swop movements, but we wanted it to be more personal and more of a surprise," she adds.

Togetherly Market is held every two or three months and it has organised four book swops since the first in May last year. Its collection of books has multiplied threefold, from about 20 when it started to 60.

A kids' section was added to the swop after the first event when the organisers realised the need to differentiate between adults and children's books.

Madam Naomi Minejima, 40, owner of Minejima & Co, a shop selling children's products at Tanglin Mall, has participated in Togetherly's book swops.

She says: "My seven-year-old son loves reading the notes people write and it's great for the kids to be curious. Something attracts you to a message written by a stranger and that little communication is super interesting. It's like minds coming together."