How does Buy/Sell/Stop Limits work?

[Ab7832]

Hey guys ,

I have only used Cex and bitstamp for buying coins by simply buying/selling on the spot  but i recently came across poloniex and wondering how it works ?


Are the buy/sell orders in line with the current price of the coin or can the sellers put anything they want ?


If a coin is on the rise , is it possible that no buy orders go through ?

Completely new to trading , any help/guide would be very appreciated/

Thanks