A purchase request, sometimes called a requisition, is the moment when saying no is still free. Once an order has gone to a supplier, or worse once goods have arrived, refusing costs a relationship and often money. Everything else about request processes is detail; the reason they exist is that this is the only point where the decision is genuinely reversible.
What a request is for
To let somebody with budget responsibility decide whether the organisation should spend this money, before any commitment exists. It is not a check on the price, which purchasing handles, and it is not a check on the invoice, which payables handles. Confusing it with either of those produces a process that asks the wrong person the wrong question.
Why the timing is the whole point
An organisation that only approves at the invoice stage has moved the decision to a moment when the answer is effectively predetermined. Approvers in that position learn that their signature is a formality, and they stop reading. Approving at request time keeps the decision real, and it keeps the approver engaged for the cases that actually matter.
Keeping it light enough to be used
What, how much, which budget, when and why. Requesters are not finance staff and a heavy form drives people to buy on a card instead. Speed matters as much as simplicity: a request answered the same day is a process people follow, and one answered in a week is a process people learn to bypass.
Questions people ask about purchase request
Is a purchase request the same as a purchase order?
No. The request is internal and asks permission; the order is external and makes the commitment. The request is approved, then converted into an order.
Do all purchases need a request?
Most organisations set a value threshold below which one is not required, because the administration outweighs the control. Set it deliberately rather than leaving people to guess.
Who approves a purchase request?
Usually the budget holder for the cost centre, against a value threshold from your delegated authority.