Due to having been asked (by someone). I'm only going to the dinner party at my mother's request. Molly has been invited at the bride's request.

If one asks. Extra pillows are available by request at the front desk.

Whenever one requests or demands something. Our client reserves the right to withdraw the license to use our her writing in your anthology on request.

Greatly sought after; desired or required by many people. To the surprise of some, the product has been in request since it was first released. Now that the property market has begun to boom, construction workers are in request.

To express a desire to obtain something from someone or something else. Typically used when something specific is being requested ("of" is more often used after "request" when the thing is vague or unspecified). I've requested a new security pass from the company, but I won't be able to access the building until it arrives. We'll need to request the documents from him before we can conclude our audit.

To express a desire to be granted something from someone or something else. Typically used when the thing being requested is vague or unspecified ("from" is more often used after "request" when the thing is specified). If you're done requesting favors of me, I'll thank you to let me get back to work. I try not to request too much from my coworkers.

To express a desire for one to do something. I'm going to request them to transfer me to a different office if things with my coworker don't improve. They requested me to file the report by the end of the week.