Surge protectors protects the items plugged into it by absorbing the electrical surge, especially when your power goes out and then comes right back on. They are rated by the amount of surge they can absorb that is why you have various "joles" (pronounced jewels) The USUALLY have some type of insurance with them. This will be printed on the box. Not all power surges will trip your electric breakers. They also help protect from LOW AMP DRAWS.
A low amp draw is when your power "dims" down when something comes on and then returns to normal. Your surge protector will "store" some energy so when the power goes down your items will remain the same. Electronic items are damaged more from a low amp draw than a power surge.
When using a surge protector, the items that require more power should be plugged in nearest the power source, where the power cord comes into the protector. Be watchful of WHAT is plugged into the protector. If you have a sewing machine plugged into the protector, don't plug your iron into the same strip. Irons are power hungry items just look at the wattage of the iron. Irons are usually 1000 watts and up. Usually when the iron kicks on to heat, power to the other items is compromised. This can cause damage to circuit boards in other items. Also, because of the wattage of an iron, it is better to be plugged directly into the wall and preferably into another socket than the protector.
It is also a good idea to replace the surge protector every 12 to 18 months. They do wear down. There are constant surge and low amp draws in electricity. These may not be enough to trip your breakers but can be enough to damage other things not protected. Good example of this fact is a light bulb.
Since we are on this subject, please review your home owners or content insurance. The insurance with the protector is not much so don't depend on that. Talk to your insurance agent. Most insurance policies put a "cap" on the amount to be paid for certain items. Today sewing machines go into several thousand dollars but your insurance policy may only pay $150 because of the "cap". You may be thinking you don't want to pay out more money for insurance but believe me when I say it is money well spent. You may say you have "replacement insurance" which is great but they still have a "cap" on payout! Whenever you buy additional equipment be sure to talk to your insurance carrier to make sure it will be covered as well.