DAY ORDER:
An order to buy or sell securities that expires unless it is executed or canceled the day it is placed.

GOOD UNTIL CANCELED ORDER (GTC): 
An order that does not expire at the end of the day it is entered.  Rather, it remains in force until it is either executed or canceled.  Be sure you cancel any existing GTC orders if you replace it with a new order.

MARKET ORDER: 
An order to buy or sell a security at the best available price.  There is no guarantee that you will receive a specific price. Usually a market order is executed at or near the price of the last reported sale. 

LIMIT ORDER: 
An order to buy or sell a security at a specific price or better. A limit order to "buy" cannot be executed at a price above your limit, nor can a "sell" order be executed below your limit.

OPEN ORDER:
An order that has been placed, but has not been executed or canceled.

STOP ORDER:
An order to buy or sell a security at the market price once that security has traded at a specified price, called the stop price.  

STOP LIMIT ORDER:
An order to a securities broker with instructions to buy or sell a security at a specified price or better, but only after a given stop price has been reached or passed.

BUY A CALL:
A call option gives the owner the right to buy the underlying stock at a given price (the strike price) by a given time (the expiration date)

SELL A CALL:
A call option gives the owner the right to sell the underlying stock at a given price (the strike price) by a given time (the expiration date).

BUY A  PUT:
A put option gives the owner the right to "put"  the underlying stock to a buyer at a given price by a given time.

SELL A  PUT:
A seller of an option requires the client to purchase  the underlying stock from a seller at a given price by a given time.

CASH ACCOUNT:
An investment account which you must pay in full for any purchases by the settlement date.

MARGIN ACCOUNT: 
An investment account which allows the client to purchase securities with funds borrowed from the firm at a specified interest rate.