Jumping up at people is an inherited instinct for a dog. In the wild it is normal for a dog to greet returning pack members by licking their faces. For a dog it tries this when a friend or family member comes in. They cannot reach the persons face without jumping up.As a puppy it is inadvertantly encouraged, when the human comes home the pup runs to greet them, the human allows the puppy to jump and actively encourages it by making a fuss of it. The pup then learns that is the way to get attention, so has learnt a new bad habit that the owner now has to train out of the dog.It may be cute to see a seven or eight week old puppy doing this, but, that puppy is going to grow into a full sized dog and it is then that the owners find the habit annoying and trouble is inevitable.A lot of people actually don't like dogs and everyone has friends that hate a dog jumping up at them. If you are dressed up ready to go out, you automatically push your dog away so that it doesn't ruin your good clothes, attention has been sought and given. Dogs do not see new or good clothes, all they see is you or your friends who normally make a fuss of them when they jump up.Now you have to re-train your dog after allowing it to get away with the bad habit for so long.Firstly when your dog runs to you on your arrival, try to get it to sit, if this fails, turn your back on the dog. when the dog has stopped being quite so excited, again try to get it to sit. the moment it's bottom touches the floor praise it verbally 'good boy' or 'good girl' will suffice. Don't touch your dog. This gives the signal that it can then jump up. Turn your back on it and do something else, make a cup of tea or peel potatoes, anything but give your dog attention.When you are out and about with your dog and you meet someone, a friend or just another dog walker, be prepared. When you get within 2-3 feet of the other person get your dog to sit. The moment it does praise it verbally. Keep it in the sit position, if it tries to jump up move away from the other person. Keep this up until your dog sits calmly while you talk to the other person. When you move off, praise the dog and give it a quick stroke and maybe a treat.You must get everyone that interacts with your dog to do this or you will never get the habit out of your dog.A dog cannot jump and sit at the same time, so always praise and treat him profusely when he sits on the first command. He will see this as a great way to possibly get a treat, but definitely some attention, so will eventually be as eager to sit as your are to have him do it.Do not speak to your dog or acknowledge your dog when you come in until he is sitting waiting for you to praise him. You can also walk swiftly towards your dog, this will confuse him and put him off balance making him unsure and stopping him from jumping up at you. This done with the sit command should get your dog doing your bidding without question. Don't forget to praise him when he does sit or he will forget to do it.Putting your knee up to stop your dog will not work, your dog will jump up at your side instead. Do not push your dog away from you, contact has been made and he has won, he got what he wanted, attention. Turn your back, it's your face he wants to lick.Always praise your dog if it sits without being commanded to, it will gradually learn that this is what gets your attention and that is the dogs purpose.Positive re-inforcement works everytime, train your family as well as the dog. if it doesn't jump up at them, it shouldn't jump up at anyone else either.