Every week without fail, Gracia Imperial brings her 16-month-old daughter to the Millennium Library. She says the library is always very well stocked.

"There's a wide range to the collection here," said Imperial. "And every week we find new books that are really interesting. And they're new!"

In fact, the Winnipeg Public Library adds a thousand new titles to its collection every week. But since there isn't space for that much material on the shelves, the library must also remove items each week.

"The fancy term is collection management," said Barbara Bourrier-Lacroix, the Winnipeg Public Libraries’ collections librarian. "We call it weeding."

Librarians across North America use an intricate process to determine which books will be withdrawn.

"And they have a fun little acronym to help you remember as you go through your collection," said Bourrier-Lacroix. " It's mustie, or M-U-S-T-I-E," she spelled.

According to the Ohio Library Council:

M stands for misleading, books that may be factually inaccurate or out of date.

The U stands for ugly, such as a worn out or damaged book.

S stands for Superseded. That's when a title can be replaced by a new edition.

T stands for trivial, where a book was poorly written or just popular for a short period of time.

I is for irrelevant to the needs and interests of the community.

E stands for elsewhere, meaning the same information is available in another format, or at other library.

Taking all these factors into consideration, a decision is made over if the item should be weeded from the collection.

"It's constant upkeep," said Bourrier-Lacroix. "That's what we do."

So people like Gracia Imperial and her daughter can keep finding something new or exciting to read at the library.