Hi,

In a way, a capacitor is a little like a battery. Although they work in completely different ways, capacitors and batteries both store electrical energy. you know that a battery has two terminals. Inside the battery, chemical reactions produce electrons on one terminal and absorb electrons on the other terminal. A capacitor is much simpler than a battery, as it can't produce new electrons -- it only stores them.

    Known for storing a short-lived jolt of electricity essential to the successful operation of electrical circuits in devices and appliances ranging from PCs to microwave ovens, cell phones, and televisions, the capacitor is in the midst of a major, ongoing upgrade of its energy storage capabilities. After nearly two centuries in which batteries have been the obvious choice for storing usable amounts of energy, high-end capacitors, known as ultracapacitors, are poised to challenge them in a growing range of applications.

The conducting plates of capicitor are charged by respective terminal of the battery and, hence gain same charge (+/-) untill the potential across capicitor became same as on the battery.