Gandalf The Grey&White

Gandalf is one of five wizards known as the Lstari he is very wise and accompanies many people on different adventures.

who is gandalf
Gandalf is a wizard full of the element of wisenes he is rather fond of the Baggins family who quite often speaks in riddles (as Aragorn says). Gandalf accompanies Frodo in the fellowship of the ring but he ends up falling into shadow with the Belrock so frodo does not see Gandalf until the return of the king because Frodo does not witness Gandalf turning into 'Gandalf the white' he only sees him as 'Gandalf the grey'.

Gandalf and Bilbo Lonely Mountain
Gandalf contributes in the adventure of the lonely mountain. He ends up leading thirteen Dwarves and one hobbit (Bilbo) to the lonely mountain helping them find the correct path to the place without the Dwarves and bilbo getting lost. He is very wise in the book as he makes sure everyone is safe an sound and calls upon the great eagles to help them as they are being attacked by the wargs and the goblins. If it wasnt for Gandalf The dwarves would not get as far as they did as he helped them through the route of the lonely mountain.