An orphan is an object with no known parent. Orphan also frequently refers to a block that is not in the longest known blockchain.
Orphan - A block whose parent block is unknown. The term 'orphan block' is also frequently used in place of the term 'stale block'.
Stale Block - A block that is valid but does not extend the longest chain.
##High signal links 2015-08-29 Requesting parents for orphan transactions
2015-08-29 Adopting block chain orphans
2015-08-30 How small blocks make deliberate orphan mining more costly
2014-11-15 What is the longest blockchain fork that has been orphaned to date?
2014-11-16 How to avoid getting stuck in orphaned chains?
2015-08-29 Propagating orphan block headers
##Low signal links 2015-08-29 How a floating blocksize limit inevitably leads towards centralization
2015-08-29 Reducing the chance for random reversal
2015-08-29 Detecting and handling fork events
2014-11-15 Chain reorganization
2015-03-09 Sidechains talk
2015-08-29 Decoupling transactions and POW
#####Contributors Jinglan Wang