Straddles:

A straddle is when you buy both a call and a put option at the same in the money strike point. A buyer might want to buy a straddle when they believe that the price of an underlying stock is about to move drastically but are unsure which direction the drastic change will occur in. Buying both a call and a put seems inefficient but when the stock price moves drastically, the gains from one option will offset any losses from the other option and provide you with a profit.

Snapchat for example, tends to move drastically after earnings either dropping in price or rising up in price. So a buyer would typically buy a straddle a week before earnings. It is important that you do not buy a straddle a few days or a day before earnings because most likely that stock's volatility is incredibly high and after earnings come out, the volatility will drop and so will your contract's worth.

Strangles:

A strangle is when you buy both an out of the money call and an out of the money put option. You use strangles for the same reason as you would buy a straddle but strangles tend to be safer as the put and call options are cheaper but the potential for return is much lower than a straddle.

Strangles and straddles are great strategies to utilize when you believe a stock is about to experience dramatic change, but taking into account the volatility and the price of the contract is crucial as you can end up losing money even when the price of the stock moves drastically. I typically use strangles as they are much cheaper and are safer thank straddles. Below is a visual example from Robinhood of how much a stock price needs to move with a $29.50 call and a $28.00 put if you sell the strangle on expiry date and volatility remains constant.

An Iron Condor is when you sell one call spread and one put spread expiring on the same day. Meaning you buy one put, sell one put, then buy a call option and sell a call option. All four options are out of the money and the call spread and put spread are of equal width. So if the strike points of the two call options are 5 points apart then the two puts should be 5 points apart as well. Iron Condors are typically used when you believe that an underlying stock price is going to stay within a narrow range in a certain amount of time. Iron condors are the opposite of strangles and straddles and you are hoping for low volatility with an iron condor.

Iron condors can be more expensive and are not recommended for beginning traders. I personally never use iron condors as the contracts are just too expensive. The point of buying a put and a call is basically to ensure that you do not have unlimited losses and once an underlying stock reaches a certain point, you stop losing money like buying insurance for your losses.

I'm not going to get into too much depth with iron condors as I do not use them but below is a picture which should help visualize what is going on in an iron condor.