B-Trees are version of 2-3 trees, which are self-balancing. They are used to improve Disk reads and have a complexity of O(log(n)), for every tree operations.The number of Childrens/Keys a particular node has, is determined by the Branching Factor/Degree of that tree. Btrees will always have sorted keys.

• Branching Factor(B) / Degree (D): If B = n, n <= Children per Node < 2(n), n-1 <= Keys per Node < 2(n) - 1

Properties

• Worst/Average case performance for all operations O(log n)
• Space complexity O(n)

Sources to read:

• Busying Oneself with B-Trees
• Geeksforgeeks
• Rust API Docs
• Keon Algorithms
• MIT Open Course