STP

STP is an acronym used for several concepts and entities across different fields, including computer networking, chemistry, automotive consumer products, and country codes.

Spanning Tree Protocol (STP) is a network protocol used in Ethernet networks to prevent bridge loops. It creates a loop-free logical topology by selecting a root bridge and disabling redundant paths through blocking or listening states. The root bridge is chosen based on the lowest bridge ID, and ports assume roles such as root port, designated port, and non-designated (blocked) ports. STP converges after topology changes to restore redundancy without creating broadcast storms. Variants include Rapid Spanning Tree Protocol (RSTP, IEEE 802.1w), which speeds convergence, and Multiple Spanning Tree Protocol (MSTP, IEEE 802.1s), which maps VLANs to separate spanning-tree instances. While effective at preventing loops, STP can introduce delay during reconfiguration and is sensitive to misconfigurations like incorrect path costs.

Standard Temperature and Pressure (STP) refers to a defined set of conditions used as a reference for gas-related calculations. Traditionally, STP was 0 degrees Celsius (273.15 K) and 1 atmosphere (101.3 kPa). Some organizations now use 25°C and 1 atm as “standard conditions,” or 100 kPa instead of 1 atm; thus definitions vary. STP is used to compute molar volumes of gases (for example, about 22.414 liters per mole at 0°C and 1 atm) and as a baseline in thermodynamics and chemical engineering.

STP is also a brand of automotive additives and motor oil products marketed for engine and fuel-system care. The acronym has historically been described in marketing as “Scientifically Treated Petroleum” or “Specially Treated Petroleum,” though the exact origin varies by source.

STP is the ISO 3166-1 alpha-3 code for São Tomé and Príncipe, a small island nation off the western coast of Africa.