The third life begins when a person enters his grave and lasts until the Day of Resurrection. The intermediate realm is the life that is between the world and the everlasting life to come. 

When a Muslim dies it is their right to be washed, shrouded and prayed over, according to the sunnah. The community should be informed, and an announcement should be made publicly. When  person hears that someone has passed away they should say, inna lillahi wa inna ilayhe rajioon -  "From Allah do we come and to Him do we return."

The intermediate realm is the abode which lies between this world and the life to come. It is the place where the spirits of people are dominant and the physical body is secondary. People in their graves are having both a spiritual and a physical experience. Their experience depends upon how the person behaved in their lives. The better the person's in intentions, words, and actions the better experience he or she has in the grave.  

When a person enters a grave, two angels named Munkar and Nakir come to him to ask him questions: "Who is your Lord?", "What is your religion?", "Who is your Prophet?" Those who have practiced their faith will answer, "Allah is my Lord, Islam is my religion, and Prophet Muhammad is my Prophet." 

We learn from the hadith that there are three types of ongoing charity you can do in your life to experience reward in the grave. These are called sadaqa jariya. They are: continuing charity, beneficial knowledge, and a pious child.

The scholars inform us that praying for those who have died, asking forgiveness for them, and giving charity on their behalf are some of the things that Allah causes those in the grave to benefit from. 

A companion asked the Prophet Muhammad, peace and blessings be upon him, 'O Messenger of Allah! My parents have died; is there anything left with which I may be good to them? And he replied: 'There are four things: praying and asking forgiveness for them, carrying out their promises, being good to their friends, and giving proper attention to those kindship bonds which could only have been attended to by them.'

It is related that the gifts of alms, prayers, and Qur'anic recitation sent by the living to the dead reach them carried by the angels on plates of light, and adorned with silk handkerchiefs, and they say to them: 'This gift is from so-and-so.', and in this way they experience joy and delight.