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Shorting options

I trade options, but have never sold to open (short) an option. My question is this; is selling to open an option the same thing as writing an option and after I write/short/sell to open an option can I buy to close any time I want to or am I required to hold the short until expiration. It is my experience that options lose value faster than it gains so this would be a better method than buying the option. Here is a prime ex I bought some SPY very near ITM puts at the market high around 835 on the ES for 2.5 and sold them at 3.22. A nice profit but The same calls went from 2.9 all the way down to .90 cent a net profit of 2$ or over 60%.

So my question is can I buy to open any time I want, if so that is the way to go. The only downside is that you can get slammed hard if the market crashes or rises hard and you are on the wrong side.
I am no option expert, but yes you can and should re-purchase your Option that you Wrote ("write") if it moves in your favour and the value of your "write" declines significantly. Close it out when you have earned 75% of the premium received.

Also - you can and should protect yourself by purchasing an OTM Put which will gain value if the market crashes and your "write" goes quickly against you. Also - this has the advantage of reducing the margin required to hold your position.