When you're living in a suburb or an urban area you will have a small plot of land that is yours to use as you please. You could add a fire pit to use for bonfires in the summer or could plant a lavish garden. You could build a shed, or put in a pool and a poolhouse. (And if that's what you're thinking, be sure to check out Atlantis Pools for some great design ideas!) But you will want to make sure that you're staying within your property lines when adding anything to your outdoor space. This will keep you from having issues with your neighbours and from having to tear anything down.
If you're not sure of where your property lines are exactly then there are a few different sources that you can consult to find out this information. The best place to look is with your deed for the property. What you're looking for is a map with measurements for the land of your property lot. When you purchased your home you should have been given a plat with all of the other official documents. The newer your home is the more likely that you will already have this information.
If you did not receive a plat than you can still access one at your local tax assessor's office. There should be someone there who can help you find the map for property lines in your area and you can likely even make a copy of the document to take home with you. This will give you measurements for how much property you own using city owned property, like roads, as a guideline. Then all you have to do is measure your real estate to find out your exact property lines.
Usually finding the property line at the back of your property is the easiest because you can simply measure from the street. If you are not living on a corner then it may be a little bit more difficult to find the edges. You should look for indicators like utility pipes or boxes. These are usually placed along the property lines. Those that can't find any helpful markers might have to measure from the end of the nearest cross street and work their way towards their own property.
If you've already added a new deck and one of your neighbours is complaining that you have built onto their property then you should know that they are likely to win the battle if their claim is accurate. You can also be in trouble if you move into a house that has a structure over the property lines. Even if you were not the one who built it, you might be responsible for moving it.