Allah has exalted Hazrat Muhammad (SAW)( p b u h ) with many miracles.

The main purpose of these miracles was to prove the sincerity of Allah's apostle.
Muslims believe in these miracles and that these miracles are performed by Allah.
Ulemas have recorded up-to 3000 miracles performed by Hazrat Muhammad (SAW) ( p b u h )
The miracles were started with his (SAW) (p b u h )birth.
Shaytaan(Devil) could not go into skies and steal information from Angels.
He could see behind him while looking in front of him.
He did not have a shadow, either in the sunlight or the moonlight.
No flies, mosquitoes or any other kind of insects ever came onto his blessed body or clothes.
The Angels followed him wherever he walked.
When he stepped on a rock, his footprint would be left on it.
Stones used to greet the Prophet whenever he passed by through the lanes of Makkah.
AL_Quran
The greatest miracle bestowed to him was the revelation of Quran. Narrated Hazrat Abu Huraira that the Prophet (SAW) said,
"Every Prophet was given miracles because of which people believed, but what I have been given is Divine Inspiration which Allah has revealed to me, so I hope my followers will outnumber the followers of other Prophets on the Day of Resurrection. (Bukhari).

Splitting of moon:

Unbelievers asked for the proof of his prophency.
He(SAW)( p b u H) asked Allah to grant him this miracle and the moon was split, half was seen over mount Saffa and other half was seen over mount Kaikaan.
Abu jahl than asked to wait for the people Albadiah. The people of Albadiah said that they have also seen the moon split.
The Unbeliever still didn't believe this and they started saying that Hazrat Muhammad(SAW) p b u h is playing trick on them.

Hijrah and spider web:

Quraish makes the plan to kill Hazrat Muhammad(SAW).
He(SAW) (p b u h)was informed of this by Allah.
So he migrated to Madina(Yasrib).
He stayed at the cave, and the spider web was made by Allah at the entrance of cave so that Quraish, who were following Hazrat Muhammad (SAW) could not know that he(SAW) was inside the cave.

Mairaj:

Lailatul Me'raj is the night in which Hazrat Muhammad (SAW) (p b u h ) ascended to the heavens and beyond to meet his Rabb. It is a miracle that was not granted to anyone else before nor will it be granted to anyone in the future. At Mairaj, he was gifted with the prayers. Hazrat Muhammad (SAW) ummat start praying five times daily after mairaj.
Glory to (Allah) Who did take His servant for a Journey by night from the Sacred Mosque to the farthest Mosque, whose precincts We did bless,- in order that We might show him some of Our Signs: for He is the One Who heareth and seeth (all things).Qur'an, Sura 17 (Al-Isra) ayah 1.

Supplication of rain:

A man came to Holy Prophet(SAW) on Friday and said that there is lack of rain, please invoke your Lord to bless us with rain. He(SAW) looked at sky and there was no cloud and then he(SAW) invoked Allah for cloud and than clouds starts to appear in sky.
Multiplication of water:
Narrated Al-Bara: At Al-Hudaibiya there was a well, we drew all water from it not leaving even a single drop. The Prophet(SAW) sat at the edge of the well and asked for some water and with which he rinsed his mouth and than he threw it out into the well. After which we drew water, and quenched our thirst, even our riding animals drank water to their satisfaction.