Why are Harry Potter and Ron Weasley close friends?

They first met when Harry heard Ron's mother use the term "Muggles" at King's Cross, so he knew she was a witch. She told him how to get to platform 9 3/4, and Ron went into Harry's compartment on the train because "everyone else was full." He tells Harry about how he hates corned beef, but his mother always forgets, and that's the only lunch he has. So when the lunch trolley comes by, Harry orders a load of sweets and that pretty much seals their friendship.