The True Islam is based on the Holy Qur'an and the Sunnah. Sunnah is an Arabic word which means the words and actions or examples of Prophet Muhammad (peace be upon him).

Six Articles of Belief
Tawheed: Monotheism (Oneness of Allah)
Prophethood and Messengership
Holy Books
Angels
The Final Judgement Day
Predestination

Five Pillars of Islam
Shahadah: Declaration of Faith
Salah: Prayer
Zakah: Charity, paying of alms and giving to the poor
Sawm: Fasting, obligatory during the Month of Ramadan
Hajj: Pilgrimage to Makkah

The Last Messenger - Prophet Muhammad (peace be upon him)
Prophet Muhammad was the last and final Messenger of Allah. No prophet shall come after Muhammad (peace be upon him)
Allah chose Muhammad to reveal His Last Message to mankind - The Holy Qur'an - and gave Muhammad complete guidance for people of all the worlds. Muhammad (peace be upon him) received the Noble Qur'an from Allah through the Angel Jibril.

Rightly Guided Caliphs
Abu Bakr Siddeeque
Umar ibn al-Khattab
Uthman ibn Affan
Ali ibn Abi Talib

Islamic Laws (Shari'ah)
The Laws based purely on the Holy Qur'an and Sunnah of the Prophet, as embodied in the Hadith, as a source of the Shari'ah.