Some requests concern the hearer's ability to perform a task. For example, "Can you pass me the salt?" asks a yes/no question. However, this is not truly a yes/no question because the speaker doesn't expect a yes/no answer. This is a request.
Requests can be expressed as a desire. An example is "I would like you to do this now." This is a statement with the polite expression "would like" that functions as a request. If we change "would like" to "want," the request becomes stronger.
Requests can also be expressed in future tense. Consider "From today officers will wear ties at dinner." Though this is a future declarative, it is also a request. However, it is clear that in this case the hearer is not expected to deny the request. In this case the request can be analyzed as an imperative.
In certain cases, requests concern the willingness of the hearer to perform a task. For example, "Do you want to hand me that hammer?" is a yes/no question, and is also an indirect request.
Requests sometimes offer advice. For example, "You should be more polite to your mother" can be analyzed as a request. It is the speaker's desire that the hearer will be more polite to his/her mother in the future.
Sometimes requests are expressed as embedded sentences. Consider "Could I ask you to take off your shoes?" This is expressed as a yes/no question and "take off your shoes" is a clause inside the question.
A direct request is an imperative such as "Lend me a pen." To make this more polite, we can add "please." This can be changed into a question by asking "Could you please lend me a pen?"
Requests can also be expressed as permission. For example, "May I borrow your pen?" requests permission and is structured as a yes/no question.
Requests can be expressed in many different ways. They can be direct or indirect. Other types of requests offer advice, express desire, ask permission and concern ability. Requests can be categorized into many different types.