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and can they be dangerous or affect my laptop ?

While it is slightly different for e manufacturer.normally in stand by, the computer continues to run, but at a reduced state. it powers down the monitor, hard drive, network card, etc., and about the only thing it keeps running is the memory, which holds the currently programs and data. when you "wake up" the pc, it repowers ething and continues to run windows and your programs. while in stand by the computer contiues to use power. if it should run out of power (battery goes dead), it will save the memory to a file and switch to hibernation instead.when you "hibernate", the computer first saves its memory to a file on the hard drive. then it powers down ething including the memory. during hibernation the computer does not use an power. when you wake up the computer, it restarts. only instead of reloading windows and ehting like a normal boot up, it reloads the file dump of its memory and then can continue to run from the same point where it was put into hibernation.