Electrons and protons have equal, but electric charges opposite on a sign: at electrons negative, and at protons — positive. Opposite charges are always attracted to each other. You can show the most similar attraction, having pulled together couple of magnets. If the closest ends of magnets represent different poles, they will instantly meet and will be pasted to each other. If the ends are with the same pole on a sign, they will start back from each other, as politicians after hot television debate. Thus, as electrons and protons have different signs, they are attracted to each other. This attraction works as glue, at the level of a microcosm, fastening itself all matter of the Universe.
Though protons are rather static, about electrons of the similar you won't tell — they very ветрены and aren't going to sit on one place. They can — and most often and do — to move between objects. For example, to walk in dry weather on a carpet and to stop on the steel door handle; the electrons running between this handle and your palm, cause a spark which you will be able to see only sometimes, but, definitely, you will feel always. The lightning too consists of a chain of moving electrons — this time they move between clouds and the earth. All these examples of feral, wild electric energy.