There are a few key ways to know that it's time to replace your electrical outlet.

Continuous Tripping
If you see that your receptacle is being tripped without any larger-than-normal appliances or devices being plugged into it, this is a sign it's time for a replacement. Unjustified tripping could signify a few different problems including issues like water damage to the socket or worn insulation. Until you take the unit out and inspect it, it can be hard to know. Read our guide on how to find out exactly why your GFCI unit keeps tripping.

Older Structure
If you live in a house, condo, or apartment that is more than 15 years old, having the electrical outlets replaced is a good idea. Though many outlets can have a lifespan of between 15 and 25 years, some can fail as early as 5 years after they're installed. As appropriate based on your living arrangement, have the electrical outlet inspected for any early signs of problems, such as cracks, discoloration, or thinning insulation.

Slipping Plugs
If your outlet has a hard time gripping the prongs of whatever you plug into it, it's likely time to get a new outlet. Sometimes there are worn or small, two-prong plugs that will go into an outlet, but they just won't be very secure (shifting whenever the cord is moved, for example). But if you have tried to plug multiple kinds of appliance or devices into an outlet and everything just sits in the outlet or falls out—there's no secure snap into the receptacle—this likely means you have worn contacts. While contact naturally wear down over time, it's important to catch this issue quickly. Plugs that aren't secured into your outlet can cause arcing.Electricity is listed by the National Fire Protection Association as one of the top causes of house fires. Protect yourself, your family, and your property by checking for loose contacts and getting your outlets replaced as needed.

There is no difference at all. The words “outlet” and “receptacle” are interchangeable terms used in the industry. They both refer to the units where you plug in your electronic devices and appliances.  

Tamper-resistant receptacles contain an internal, spring-loaded shutter that doesn't allow foreign objects to be placed inside. The shutter makes sure that no circuit connection can be made unless the pressure on both sides of the internal shutter is even. This helps keep kids and pets safe from accidental electrocution. This feature makes a tamper-resistant receptacle perfect for schools, daycare centers, and indoor play areas. It has the same level of effectiveness (if not higher) than external outlet covers, but is more beneficial because it eliminates a choking hazard.

Decora is another name for what's commonly known as a "rocker" switch. The traditional switch type (A.K.A. "toggle switch") is smaller and protrudes out from the wall more abruptly. Like a toggle switch, the rocker switch can be set to up/on and down/off positions. Rocker switches work the same way, but they have a wider, flatter mechanism that lays almost flush against the wall. For some stylistic reasons, this may be the preferred switch type for certain projects.

Single Outlet
This outlet only has a single receptacle for electrical devices. Appropriate for rooms where there is rarely any need to plug something in.

Duplex Outlet
This outlet has two receptacles, allowing two devices to be plugged in at a time. These kinds of receptacles have become more common with the popularity of portable electronic devices such as lightweight laptops and smartphones.

Combo Outlet
This outlet is built just like a duplex outlet, except that there is only one place to plug something in. The other segment of the receptacle is used for a switch that can be connected to a light bulb or other fixture.