What are Command Blocks? ( i googled some of these..)
Command blocks are blocks that you can obtain with /give @p minecraft:command_block 1 .You can also use them to write commands it it, such as /give , /kill , and more commands. Its like the commands on the chat, but you can also use them like coordenates, with /tp and /tpa , and also for trolling. Command blocks are not avaible at the inventory. The command blocks are also used in 3 types, like Chain, Repeaters and the Impulse command blocks types.They are only activated in redstone blocks or redstone ores.
The Repeater Command Blockk Repeats the command, if you also do a redstone clock, it will repeat even more, it will do the same thing even tho.
The Impulse Command Blockk This type of command blocks can do every command block just like in chat, you write the command in the gray space bar in the top, and then write the command in there, any type of command in /? or /help.
The Chain Command Blockk The Chain Command Block can do the same things like the Impulse Command Block, i think..
The command blocks, like i said earlier are only obtained from the command /give. You cant use them on survival, but you can on creative even though.