A surge protector guards electronics from power surges and voltage spikes. It can absorb and dissipate the power of a surge so that connected device is protected.

A power strip is an extension of a single electrical outlet that provide multiple outlets, and it does not have surges protection. It may look like a surge protector and have similar benefits, such as extra outlets, but a surge protector can protect your electronics from power surges.

Yes, even the best quality surge protectors have certain life time and will have to be replaced. The equipment wears down because it absorbs power surges all the time. The protective components will degrade gradually and eventually provides no protection. When this happens, the power will not be connected to the outlets anymore.

A power surge is a spike or increase in voltage, which can damage or even destroy sensitive electronic devices in your home. Power surges are caused by different factors, including severe weather, faulty or damaged electric wiring or the sudden turning on and off of a high power electrical device like an air conditioner or large electric motor.
Strong power surges from severe weather can destroy home equipments in an instant. Even the average home can experience several hidden surges every day from various sources. The smaller surges can also cause cumulative damage to electronics and eventually lead to device failure.

The joule is the unit of energy and a surge protector's joule rating shows how much energy it can absorb. The bigger the number, the greater protection is provided. Surge protector lifespan depends on how many joules it has absorbed. But, the older your surge protector is, the more it's likely degraded.