The Secure Hash Algorithm or SHA is a family of cryptographic hash functions published by the National Institute of Standards and Technology (NIST).
Simplified Payment Verification (SPV)::
SPV or Simplified Payment Verification is a method for verifying particular transactions were included in a block without downloading the entire block. The method is used by some lightweight Bitcoin clients.
soft fork::
soft fork or Soft-Forking Change is a temporary fork in the blockchain which commonly occurs when miners using non-upgraded nodes don't follow a new consensus rule their nodes don’t know about.
Not to be confused with fork, hard fork, software fork or Git fork.
SPV (aka Simplified Payment Verification)::
SPV or Simplified Payment Verification is a method for verifying particular transactions were included in a block without downloading the entire block. The method is used by some lightweight Bitcoin clients.
Stale Block::
Block which were successfully mined but which isn’t included on the current best block chain, likely because some other block at the same height had its chain extended first.