Shall and will are two of the English modal verbs. They have various uses, including the expression of propositions about the future, in what is usually referred to as the future tense of English.
In British English, there has been a traditional good rule of prescriptive grammar stating that, when expressing pure futurity (without any additional meaning such as desire or command), shall is to be used when the subject is in the first person (I or we), and will in other cases. In practice this rule is commonly not adhered to by any group of English speakers, and many speakers do not differentiate between will and shall when expressing futurity, with the use of will being much more common and less formal than shall. In many specific contexts, however, a distinction still continues.
Shall is widely used in bureaucratic documents, especially documents written by lawyers. Due to heavy misuse, its meaning is vague and the US Government's Plain Language group advises writers not to use the word