The S band is part of the microwave band of the electromagnetic spectrum. It is defined by an IEEE standard for radio waves with frequencies that range from 2 to 4 GHz, crossing the conventional boundary between UHF and SHF at 3.0 GHz. The S band is used by weather radar, surface ship radar, and some communications satellites, especially those used by NASA to communicate with the Space Shuttle and the International Space Station. The 10-cm radar short-band ranges roughly from 1.55 to 5.2 GHz.

In the U.S., the FCC approved Digital Audio Radio Satellite (DARS) broadcasts in the S band from 2.31 to 2.36 GHz, currently used by Sirius XM Radio. More recently, it has approved for portions of the S band between 2.0 and 2.2 GHz the creation of Mobile Satellite Service (MSS) networks in connection with Ancillary Terrestrial Components (ATC). There are presently a number of companies attempting to deploy such networks, including ICO Satellite Management and TerreStar.

The 2.6 GHz range is used for China Multimedia Mobile Broadcasting, a satellite radio and mobile TV standard which, as with proprietary systems in the U.S., is incompatible with the open standards used in the rest of the world.

Band may refer to:

In Chinese and other Asian societies, a red envelope or red packet is a monetary gift which is given during holidays or special occasions.

It is known as hóngbāo in Mandarin, Ang Bao in Taiwanese, Ang Pao in Min Nan, Lei See (利市/利是) in Cantonese, Sae Bae Don (세뱃돈/歲拜돈) in Korean, and Lì Xì in Vietnamese.

Red envelopes are mainly presented at social and family gatherings such as weddings or on holidays such as the Lunar New Year. The red color of the envelope symbolizes good luck and is supposed to ward off evil spirits. The act of requesting for red packets is normally called (Mandarin): 討紅包, 要利是, (Cantonese): 逗利是.

The amount of money contained in the envelope usually ends with an even digit, in accordance with Chinese beliefs; for instance 88 and 168 are both lucky numbers, as odd-numbered money gifts are traditionally associated with funerals. There is also a widespread tradition that money should not be given in fours, or the number four should not appear in the amount, such as in 40, 400 and 444, as the pronunciation of the word "four" resembles that of the word "death" and thus signifies bad luck for many Chinese (See Numbers in Chinese culture). At weddings, the amount offered is usually intended to cover the cost of the attendees as well as signify goodwill to the newlyweds.