Hopefully we have all got lots of presents. Let’s keep them safe. For protecting/tracing other items, then the UK National Property register at https://www.immobilise.com/ lets you register valuables and helps Police get your stuff back to you.
There is always a danger of buying electronics that are not sold by the rightful owner. One useful site is imeipro.info. This lets you check the IMEI number of a phone (basically its serial number) against a list to see if it has been stolen. It also lets you register that yours has been stolen.
You can find your IMEI by dialling *#06#, on an Android by looking at settings-about phone-all specs-status-imei or for an iphone settings-general-about. Make a note of the number.