I just found it here block chain and check some more info how block chain works.. and now i saw this
https://blockchain.info/charts/n-orphaned-blocksorphaned blocks chart. but honestly i don't know why we have orphan blocks.?
I hope someone can give me idea about this or simple and easy explaination about this..
It can happen that two miners on different parts of the planet find a block at the same time or shortly after eachother. Both blocks are valid, but only one will continue the blockchain over time. The block that was not build on is the orphan.
Do you have any other explanation i searched from google but i found many discussions. but actually i still do not understand.
So if the two miners in different pool?
Yes or two solo miners if thats easier to understand. How exactly the miner is organised does not matter.
mined in the same time both blocks are valid?
Lets say you are a miner and find a block. Once you do, you send it in the network and everyone checks if its valid and if so passes the block along to others in the network. It takes some time until everyone in the networks has the block and has it verified. This is also true for other miners. Thus its possible that two different miners find two blocks. These blocks can be different, but have the same height (e.g. both are the 500,000th block). Both send them in the network and work on block 500,001.
According to blockchain i saw this "The total number of blocks mined but ultimately not attached to the main Bitcoin blockchain." So it means if you mined orphaned blocks it is valid blocks but it is not attached in blockchain?
Yes, there can only be one block #500,000, whoever finds block #500,001 first decides which is valid. Every block has a predecessor (identified by block hash). In our case each of the miners would work on top of their own block and all other miners would work on top of whichever block they received first. It can happen twice or more times in a row, but over time eventually one side will win and all other blocks become orphans.
