Who is Buddha?
In general, Buddha means "Awakened One," or someone who has awakened from the sleep of ignorance and sees things as they really are. A Buddha is a person who is completely free from all faults and mental obstructions. There are many people who have become Buddhas in the past, and many people will become Buddhas in the future.
There is nothing that Buddha does not know. Because he has awakened from the sleep of ignorance and has removed all obstructions from his mind, he knows everything of the past, present, and future, directly and simultaneously. Moreover, Buddha has great compassion which is completely impartial, embracing all living beings without discrimination. (about Buddha.org)
The word Buddha translates to "enlightened" in Sanskrit. This is a title applied to Siddhartha Gautama, the founder of Buddhism, as well as to a handful of other enlightened individuals.
Who Worships the God?
Buddha is not considered a God. Buddha is to Hinduism as Jesus is to Christianity. Gautama Buddha was born a Hindu but tried to reform Hinduism. For that reason, Buddhism has been referred to as "Hinduism lite." Buddha founded Buddhism in India, but it is much more popular in China than India where Hinduism is still the dominant religion.
It's a common mistake that Buddhists worship Buddha. Buddha is not a God, not even to Buddhists – he is a teacher or an individual who reached enlightenment.
Buddhists do not worship any gods or a God. People outside of Buddhism often think that Buddhists worship the Buddha. However, the Buddha (Siddhartha Gautama) never claimed to be divine, but rather he is viewed by Buddhists as having attained what they are also striving to attain, which is spiritual enlightenment and, with it, freedom from the continuous cycle of life and death.
At the time of Buddha’s quest for enlightenment, there were many religious practices that called for either intense overindulgence in the senses or strict deprivation such as weeks of fasting. Realizing that neither were truly beneficial, he devised what would later be known as “The Middle Way” to enlightenment, a balanced approach that emphasized inward rather than outward renunciation.