First off, you should know about your vehicle.  Not every vehicle has a keyless entry system.  If you are unsure, have your VIN handy and call a dealer service dept.  Provide them the VIN and ask them if your vehicle was manufactured with a keyless entry system.  They will generally help you with this very readily.  Many keys, and all of the remotes need programming for them to work with your vehicle.  Some can be self programmed, some can not.  No smart keys / remotes can be self programmed.   It is best to do your homework PRIOR to purchasing so you will not be expecting to receive something that the seller can not supply to  you.  Nearly all vehicles will have to have all remotes to be used with a particular vehicle programmed at the same time.  So if you purchase and additional remote to add to an existing one, they will both need to programmed at the same time. Some self programming is very easy, others ( mostly some Toyotas)  are not so easy at all and some folks may have difficulty with it if they have no patience / persistance, or mechanical ability in some cases.  It is wise to remember that all programming comes from the manufacturer that built the car.  It is not something that any ebay vendor made up for your car.  A number of folks go to dealers thinking that they are gospel, when in fact they are not always like that at all.  Some dealers litterally don't know about their own products. Others want to charge you exhorbitant fees, which is why most of us do not like going to a dealer at all.  They will often mislead you, have a host of stories, and generally tell you that your item ( ebay purchase ) is not good, wrong, will not program, etc etc, all in an effort to sell you their product at a considerably higher price.  They are then able to quickly and easily program theirs, no surprise there!  This is a take off on the classic bait / switch deal.  This is very common these days with dealers hurting so much, and many folks will fall for this unless you have the knowledge to combat them.  Many times a good locksmith can assist you, and they are often much cheaper as well.  We have had a number of folks that fell for this, and end up unhappy thinking we did not due them justice.  All of our items are tested a few times before shipping. We have programmed  a number of remotes to vehicles that people insisted were inoperable.  We have also had many people that have stood up to a dealer and found out we were correct.  We have also proven dealers wrong by actually programming units over the phone that dealers have announced were dead, no good, etc.  We try to give a great deal of information in all our auctions.....maybe too much info.  In general, we have found that a lot of folks just do not read the info, and / or do not understand how the process works for these products.  This is why we try to put the info out there in an effort to help people understand what is involved.  Do not buy a remote just because you like the way it looks, or because it looks like the one you have.  It may not work.  Many remotes look identical in appearance, but they are not the same at all.   We have cut all kinds of keys, and programmed many many hundreds of keys and remotes from nearly all manufacturers, probably many more than a lot of dealers that may only periodically do a few for their make of vehicle.  We do about 90 to 95 of the vehicles out there, so we are not just a seller but we also have a great deal of hands on experience that many others do not have.   In summary, know about your vehicle, read the info provided by ebay sellers, and know that generally these handy items can be bought on ebay for much less than dealer prices.  Even if you need to pay for the programming of these items to your vehicle, you can likely save a good amount of money by purchasing on ebay.  We hope that if you have taken the time to read this, that you have found it to be informative and helpful no matter who you choose to purchase from.