Weekly Options or "weeklys" are options that expire each week. Traders trade these options to take advantage of fast decay since time is running out on these contracts. There is no free lunch trading weeklys. If the underlying price moves up or down very fast the impact will be a steep change in the option price. This leaves little time to adjust. So if you remember there can be added risk trading weeklys you will keep a eye out for the best candidates including looking at LOW POA to limit the chance of being assigned.
Here are a few links to recent posts on the site regarding weeklys:
In our Advanced Option Screener you can either set a Friday expiration date or select Weekly Options from the Sector drop down list.