The term of Shia in the Arabic language means the follower.
The holy Quran says:
(صافات: 83) وَإِنَّ مِنْ شِيعَتِهِ لَإِبْرَاهِيمَ
Indeed Abraham was among his followers,
Then shia means follower. Shias are Muslims who believe that the Prophet of Islam (pbuh) had appointed his successor before departing this life in some special occasions.
The honored Prophet (pbuh), of course, applied this title to Imam Ali‟s followers in his lifetime, where he referred to Ali Ibn Abi Talib (a.s) as:
والذي نفسي بيده، ان هذا وشيعته لهم الفائزون يوم القيامة
(By Allah, Whom my life is in His hand, he [Ali (a.s)] and his followers are prosperous on the Day of Resurrection.)
Therefore, the term „Shia‟ is applied to a group of Muslims, who were so-called due to their belief that God appoints His caliphs. This group has already remained believing in following the Prophet‟s Ahlul-Bait (a.s).
Shia muslims believe Shahada (Faith) as the most important belief.
Shias believe to Allah, All messengers, Last messenger means the Holy prophet of Islam and his Quran.
Shiites believe in the Day of Resurrection, heaven and hell and divine justice.
Shias adhere to the teachings of Holy Prophet(s) and the religious guidance of his family who are known as Shia Imams or Ahlul Bayt and the last savior, Imam Mahdi.
They also perform:
Shia and sunni people are Muslims but enemies of Islam like to divide Muslims and creat hatred between them.