Heaven is real.
In heaven: He will wipe away every tear from their eyes; and there will no longer be any death; there will no longer be any mourning, or crying, or pain; the first things have passed away. - Revelation 21:4
We will be with God: Beloved, now we are children of God, and it has not appeared as yet what we will be. We know that when He appears, we will be like Him, because we will see Him just as He is. - 1 John 3:2
Heaven is beyond human description: Things which eye has not seen and ear has not heard, and which have not entered the human heart, all that God has prepared for those who love Him. - 1 Corinthians 2:9
In Revelation chapter 21 John gives this description of the New Jerusalem:
And he carried me away in the Spirit to a great and high mountain, and showed me the holy city, Jerusalem, coming down out of heaven from God, having the glory of God. Her brilliance was like a very valuable stone, like a stone of crystal-clear jasper. It had a great and high wall, with twelve gates, and at the gates twelve angels; and names were written on the gates, which are the names of the twelve tribes of the sons of Israel. There were three gates on the east, three gates on the north, three gates on the south, and three gates on the west. 14 And the wall of the city had twelve foundation stones, and on them were the twelve names of the twelve apostles of the Lamb. - 1 Corinthians 2:9
In John 14 Jesus assures His disciples that He has prepared a place for them in heaven:
Do not let your heart be troubled; believe in God, believe also in Me. In My Father’s house are many rooms; if that were not so, I would have told you, because I am going there to prepare a place for you. And if I go and prepare a place for you, I am coming again and will take you to Myself, so that where I am, there you also will be. - John 14:1-3 (NASB)
In the King James Version the second sentence is translated as "In my Father's house are many mansions..." This is where the idea of our living in mansions in heaven comes from. The Greek word translated as "rooms" in the NASB and "mansions" in the King James, means “the act of staying or residing." Jesus is not promising us that we will have mansions in heaven. He is saying there will be many people abiding together in the Father's house (heaven). Jesus is saying we will have lots of company in heaven.
What Is Heaven Like?
One thing we know about heaven is that we'll be with God, and sin cannot exist in the presence of God. In Exodus 33:20 God tells Moses:
"You cannot see My face, for no man can see Me and live!” - Exodus 33:20
We know that everyone who has disobeyed God has earned the lake of fire, the second death (Revelation 21:8). That's every one of us. Only those for whom Jesus died, wiping away their penalty for sin, making them free from the stain of sin, will enter heaven. Revelation 21 straight out says that sin will not ever enter heaven:
But nothing unclean will ever enter it, nor anyone who does what is detestable or false, but only those who are written in the Lamb's book of life. - Revelation 21:27
Wasn't the original creation free from sin? And yet, Adam disobeyed God and brought sin into the world. Might that happen again?
It will not happen again. The situation has changed. We are united with Christ in the cross and His resurrection. Our sin and sin nature have been wiped away. God has destroyed sin and eliminated the possibility of sin in heaven. Look at it this way... all believers want Jesus as their Lord. That means our desires are to fully obey God, although we are imperfect in doing so in this life. In heaven our desires to obey God will be perfectly realized.
A Picture of Heaven
We're now starting to see a picture of heaven. We will be with God, the source of all good things, and nothing but good things (1 John 1:5). We'll be protected from sin and sinning by God. There will be no death (Revelation 20:14 & 21:4). No curse (Genesis 3:17-19 & Revelation 22:3) nor corruption (Romans 8:19). We will worship and serve God (Matthew 4:10 & Revelation 22:3) We will be learning and never stop learning (Romans 11:34, Ephesians 3:18-19) and we will meet others and get to know them (fellowship - 1 Corinthians 13:12 & Revelation 7:9).
What is heaven physically like? Is it a place in the clouds? That's not how Jesus describes heaven. He says it is like a beautiful park.
And He said to him, “Truly I say to you, today you shall be with Me in Paradise.” - Luke 23:43
The word translated as "Paradise" is "paradeisos" which means a park, forest or orchard that is a place of happiness (Eden). That's how Jesus describes heaven.
As you can see, heaven is a wonderful, complex place with a depth of experiences. There is the city of New Jerusalem and a park-like setting... and throughout all of heaven we are in the actual presence of God.
How Does Someone Get To Heaven?
No one deserves heaven. Every one one of us has disobeyed God, bringing on ourselves the just penalty of eternity in hell. No exceptions: "for all have sinned and fall short of the glory of God." (Romans 3:23)
There is only one option. Repent (turn away from disobeying God) and trust in Jesus Christ (believe) as having fully paid your penalty for disobeying God. "For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord." - Romans 6:23
The answer is ALWAYS JESUS.
Links to information on other web sites:
Will It Be Possible For Us To Sin In Heaven?
Going to Heaven - How Can I Guarantee My Eternal Destination?