Friendship is like a rose plant.
If our hands are not positioned properly thorns bite us
If our hands are positioned carefullly flowers enlight us.

Friendship is the greatest relationship which helps to overcome any hardship.
Who is a friend? Refer to my poem for my opinion.
http://www.authorsden.com/visit/viewpoetry.asp?AuthorID=7336&id=10698
There is a sanskrit poem on true friend:
paapaannivaarayathi, yojayathe hitaaya, guhyam nigoohati, gunaan prakateekarothi, aapadgatamcha na jahaati dadaathi kaale,
sanmitra lakshanamidam pravadanti santaha.

According to this verse, a good friend is he who protest,prevent us from doing wrong things, who wishes for our welfare, who hides our secrets, who reveals our good qualities and greatness, who will be with us in our good times and bad; who will not leave us in our trying times.

Friendship can be formed with any person. Right from the kid to an aged person. There will be no such a person in this world without a Friend. We can express everything to our friends.

Friendship with everyone is not equal. We have many friends. But friendship with one friend is different with the other one. We like someone for their goodness. Someone for their creativity. Someone for their intelligence. Someone for their sense of humour. We like someone for no special reason but we have strong bond with them.

But everyone we mention as friends are truly friends? I don't think so. We usually call everyone as friends. We call our classmates and everyone whom we are introduced to as our friends. They are only acquaintances. As far as I am concerned, I wish to be alone than in a indifferent company.

One litmus test for a friend is how he/she behaves in our trying times. Who really care for us, concern about our whereabouts. Guard us. Direct us. Treat us as a special person in this world.

To continue friendship with anyone is: We shouldn't expect anything from them. Not even the care and concern we show towards them. If you like anyone, you be friend with them, but don't expect anything in return.

The best option is to be a friend to ourselves. Next is making our hobbies as our friends. Either reading books, listening to music, painting, collecting stamps etc.,etc. Another best thing is making God as our Best Friend.