Hello is a greeting in the English language. It is common between two people in a non-formal (informal) setting, but can also be used in a formal setting. There are also many other ways of saying "hello", for example, a we of the hand, a salute or a bow (both very formal), a handshake (a little formal), or a high five (very informal). Saying "hello" is a sign of politeness, especially when it is said in a friendly way. "Hello" was first used in writing in about 1833.
Many people say "Hello" when they answer a phone call.
Other greetings like "hello" include; Hi, Hallo, Hiya, Howdy, Hey, Howya, 'Sup, Yo, 'Yello, Herro, Greetings, Good day, What's poppin', G'day mate, Top of the mornin' to you, Ay-up, what's up mate, what's good, and great weather we're hing. There are also many more.
"Goodbye" is a shortened version of the religious farewell expression "God be with ye", which indicates the user's religious belief, usually in a single god. Similar expressions exist in other languages such as: adieu, adieus, adieux, adios. These terms also possess religious undertones as they are derived from the Latin word "Deus", meaning "god". This of course does not always mean they are religious.