What is a Orphan Block?

[Sonu_titu]

Couple of weeks before one of my transaction was declined(did not find a better word) and when I asked my wallet provider I go to know that it is because of Orphan block. When I asked more to the wallet provider they said it is because of the time lag.

What is this Time Lag?
Did I do something wrong?
The transaction fee I paid was small?
Does this happen frequently? How often?

Funds were back to my wallet but, I am not aware of Orphan block. Can someone please give me some light on this?

[mocacinno]

When two miners find a new valid blockheader for height x, only one of those blocks can become part of the main chain... The other is orphaned.
If the orphaned block contains other transaction than the block that became part of the main chain, these other transactions will remain unconfirmed untill at least one more block is found and added to the main chain. The transactions that were present in the orphaned block but not in the block on the main chain will still be in the mempool of most mining nodes, so they'll be added to a block later on (unless there's a problem with the transaction, like dust outputs, insufficient fees, improper propagation troughout the network,...)

However, as a "normal" user, you shouldn't worry about this... If you sell something expensive just wait for 2 or 3 confirmations before you send the goods or service.

[CryptoInsights]

Orphan blocks are blocks which are valid and verified but not accepted into the blockchain network. There are no funds lost in this case. (as no funds are lost in this process you received back your funds).

What is this Time Lag?

Basically, to confirm or validate of any block into the blockchain occurs only after the block is spread/sent across all the nodes available. The Time lag is the time that was taken while the block was sent across the nodes.

[Kavelj22]

This is really weired how users don't make simple searches before posting such nooby questions here.

On the basis that you are a paralyzed newbie user in the crypto world and in the internet as whole, let's try to answer your question in few simple words:
Orphan Blocks are valid blocks which are not part of the main chain (blockchain) as explained in previous posts. They can be naturally occur when two  blocks being produced at the same time or maybe also caused by an attacker attempting to reverse transactions with enough hashing power.

To make it more easy for you to understand, check those useful links:
Definition of "Orphan Block". Wikipidia
Explore Orphaned Blocks. blockchain. com
Bitcoin Q&A: Orphaned blocks and stuck transactions. Youtube video

For more questions, please post it in Development & Technical Discussion board.

[Zooming]

Orphan blocks are blocks that are no longer on the longest (most computationally difficult) chain. All the transactions that were in an orphan block are returned to the pending transaction pool.

[Labonikhatun]

I think orphan blocks are those blocks which are not accepted into the blockchain network due to a time lag in the acceptance of the block in question into the blockchain as compared to the other qualifying block. However, the orphan block is most commonly linked to the popular bitcoin cryptocurrency network. In case, if any valid transactions exist on an orphan block, they are added to the next valid block accepted on the blockchain.

[Jet Cash]

It might be easier to understand if you guys think of the chain splitting when two blocks are mined at the same time, and both are built on the highest current block. The miners will start to mine further blocks on one of them. and the new block will be a confirmation of that "fork". Miners will stop building on the shorter of the two forks, and it will die. All of the blocks in that fork will become ophaned blocks. Any unconfirmed transactions should be returned to the memory pool, and will be added to subsequent blocks in the new dominant fork.