Binary options market price is the current value of the financial instrument as per the asset movement. The market price fluctuates, and it should be high or low than that of the strike price in order to give you your trade results.
Suppose you have traded upon the price hike of an asset. If yes, then the market price should be higher than that of the strike price in order to let you win profit. And if you have placed a trade on the price drop, the market price should drop below the strike price to let you win profit.
So, it is a crucial element of consideration when you are trading with binary options. The value that fluctuates is called the market price, while the theoretical value on which the trade happens is known as the strike price. The strike price is the market price at the moment when you place the trade. And it remains fixed irrespective of the market price fluctuations during the expiry duration.
Examples for better understanding
Suppose your market price at the time of trading is $100, then that becomes your strike price. After placing the trade on the market price hike, the market price fluctuates naturally depending upon the asset functionality. Now, if the market price rises beyond $100 (strike price), then you will win the trade. And if it falls below $100, then you will lose the trade.
Hence, this is the practical definition of binary options market price!