Selling items online (through Facebook) to downsize.

I am retired and am downsizing. I have many items that I'd like to sell to clear out my space. There is a Facebook group set up specifically for buying and selling these items. The payments are typically made through PayPal and will be sold for considerably less than I paid for them. Will have I to pay taxes on this? Would I have to pay taxes if I sold them on eBay?

Thanks!

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