Salaam Farrhana, Naila, Ali and Hussain,
Thank you for your question.
First of all, let me point out that the afterlife is not a philosophical matter in Islam. It is a reality that every prophet sent to mankind, peace be upon them all, has warned his people about. There are numerous references to the Hereafter in the Qur’an and the hadith of Prophet Muhammad (pbuh). Many descriptions and warnings about the Day of Judgment can be found in both sources and we, as Muslims, take them to be fact, not conjecture or philosophy.
A belief in life after death in Islam is a pillar of faith. It is a main rationale for the religion of Islam itself. In saying this, I mean that there is not much point for Allah to give us the beautiful gift of Islam as a way of life, if there is no continuation of life in the Hereafter.
If there were no belief in the Hereafter, people would feel free to do as they please, at least to the limits that other people would set for them and enforce. They would only have their personal desires as a guide for behavior and belief. They would not feel accountable for the deeds that are hidden from the knowledge of society. A belief in the Hereafter helps us to keep in mind that there is a God, Allah, and He has prepared a great reward for those who do good and a severe punishment for those who only follow their selfish desires.
Death is actually just a transitional point, where we leave this worldly life and enter into a different, everlasting life. For some - I ask Allah that we would all be in this category inshaAllah - the next life is a pleasant existence, which is much better than we could even ever imagine it could be. For others - I ask Allah that none of us would end up in this category - the next life is a terrible existence, which is unimaginable in its torments.
The Day of Judgment is a fixed day in the future when everyone will be brought to stand before their Creator, Allah, to account for all that they did in their life. Those who believed in Him and practiced righteousness, will be rewarded and those who were irresponsible and practiced evil will be punished severely. Many people, however, have already passed away and are still waiting for the Day of Judgment in their graves.
For those who believed and did good in this life, their grave will be spacious and well lit. Their deeds will come to them in the form of a handsome attendant who will speak kindly and keep them company till the Day of Judgment. From their graves, they will be able to see their place in Paradise. They will beg Allah to bring the Day soon, so that they can receive their reward as soon as possible.
For those who did not believe in Allah or did evil in this world, their grave will be very dark, tight and restrictive, so much so that they will feel their ribs crossing over each other in the middle of their chest. Their deeds will come to them in the form of an ugly and mean attendant. From their graves, they will be able to see their place in Hellfire. They will beg Allah not to bring the Day of Judgment so that they would not suffer what is in store for them.
There is a wealth of information available to those who would like to know more about this key issue for all of mankind. All we need to do is read the Qur’an and books of hadith that deal with this subject. The truth about the next life is easily accessible in these two sources.
I hope this has helped you to understand the subject a little better. I pray that Allah guides us all to what pleases Him and benefits us in this life and the next, thank you.