Are spot market ,regular market and ready market same in stock trading if not then what is the difference ? and is short selling margin trading ?
So, the term "ready market" simply means that a market exists in which there are legitimate buy/sell offers, meaning there are investors willing to own or trade in the security.
A "spot market" means that the security/commodity is being delivered immediately, rather at some predetermined date in the future (hence the term "futures market"). So if you buy oil on the spot market, you'd better be prepared to take immediate delivery, where as when you buy a futures contract, the transaction doesn't happen until some later date. The advantage for futures contract sellers is the ability to lock in the price of what they're selling as a hedge against the possibility of a price drop between now and when they can/will deliver the commodity. In other words, a farmer can pre-sell his grain at a set price for some future delivery date so he can know what he's going to get regardless of the price of grain at the time he delivers it. The downside to the farmer is that if grain prices rise higher than what he sold them for as futures contracts then he loses that additional money. That's the advantage to the buyer, who expects the price to rise so he can resell what he bought from the farmer at a profit.
When you trade on margin, you're basically borrowing the money to make a trade, whether you're trading long (buying) or short (selling) on a security. It isn't uncommon for traders to pledge securities they already own as collateral for a margin account, and if they are unable to cover a margin call then those securities can be liquidated or confiscated to satisfy the debt. There still may even be a balance due after such a liquidation if the pledged securities don't cover the margin call.
Most of the time you pay a fee (or interest rate) on whatever you borrow on margin, just like taking out a bank loan, so if you're going to trade on margin, you have to include those costs in your calculations as to what you need to earn from your investment to make a profit.
When I short trade, I'm selling something I don't own in the expectation I can buy it back later at a lower price and keep the difference. For instance, if I think Apple shares are going to take a steep drop at some point soon, I can short them. So imagine I short-sell 1000 shares of AAPL at the current price of $112. That means my brokerage account is credited with the proceeds of the sale ($112,000), and I now owe my broker 1000 shares of AAPL stock. If the stock drops to $100 and I "cover my short" (buy the shares back to repay the 1000 I borrowed) then I pay $100,000 for them and give them to my broker. I keep the difference ($12,000) between what I sold them for and what I paid to buy them back, minus any brokerage fees and fees the broker may charge me for short-selling.
In conclusion, a margin trade is using someone else's money to make a trade, whether it's to buy more or to sell short. A short trade is selling shares I don't even own because I think I can make money in the process.
I hope this helps.