'May' is a modal verb mainly used in formal contexts. It is used to give and ask for permission, talk about possibilities, and offers. Take a look at the following examples:

'Shall' is a modal verb used to talk about necessities, give suggestions, and make offers. Have a look:

'May' and 'shall' are used to make offers. Offers are statements used to show our willingness to do something. They are followed by first-person singular or plural pronoun (I and we). For instance:

Modal verbs can be used to create negative or interrogative sentences.
When we want to make a negative sentence, we add 'not' to the modal verb as shown in the pattern below:

Look at the following examples for clarity:

Questions are made through the inversion of the modal verbs with the subject. Take a look:

We use 'may' to give and ask for permission to do something in a formal context. Take a look at the following dialogue:

'Shall' is used to talk about formal obligation in documents and formal contexts. Have a look:

We use 'may' to show a chance of occurrence in the present and the future. In this case, we are not certain about the outcome. For instance:

'May' is used at the beginning of the sentence to express wishes, condolences, or say prayers. Take a look at the following examples:

'May' is used with conditionals type 1 to talk about real situations with real outcomes. These situations often have a high chance of occurrence. For example: