Most offices will rely on a few basic items that they can never afford to be without. Computers, telephones and office furniture are all accepted as necessities for any office, but there are simpler things that, if unavailable, can prove costly in terms of lost revenue for a business. Email is obviously required by any business in the 21st Century, but paper is still important and, as regards office supplies, arguably the most important. As most people with access to a personal computer have a printer as well, printing anything from a small print run of commercial leaflets to letterheads should be straightforward and cut out the need for a professional printer. A healthy supply of paper also means that an idea can be conceived and executed in a very short period of time. Paper is a necessity in an office, because it's still often required for documentation and invoices. Paper also offers a quick way of getting accurate instructions to a fellow worker, either by writing the instructions down or by printing them out. There should always be an ink cartridge or laser toner cartridge on hand in an office, for any unexpected heavy printer use. There's few things more irritating to a computer user than happily printing away, only to unexpectedly run out of ink. For a very small business, a lot of valuable time can be wasted if there's only one printer in operation and that can't print until a new cartridge or toner has been installed. Envelopes, like paper, go hand in hand and all offices should have a good supply of them and in varying sizes. Envelopes will be needed for anything from enquiries about your business, which may involve requests for catalogues or a general price list, to sending out invoices. Medium to large-sized envelopes will be needed for this purpose. Sometimes businesses will still have to rely on mailing cheques for stock and so small envelopes will be required in this instance. Pens and pencils remain useful for writing down things such as phone numbers and addresses, which have been received via the phone. They will also be required when taking an order by phone and can be an even quicker way of passing on information, than by e-mail for instance. Without a pen and pencil to verify an order or address, memorising the information can result in inaccuracies and mistakes in filling in the order. Some types of office supplies are never given a second thought, but play an important part in helping an office to run smoothly. Tape, including Sellotape, should always be in an office and can come in useful in a number of different ways. Tape can be used to seal an envelope, which had to be re-opened before sending, to mending a favourite broken pen or pencil. Other items that should always be at hand in an office are a stapler and a hole punch. A stapler or hole punch will come in useful after a few pages have been collated and then need to be kept in order.