In electronic design, a semiconductor intellectual property core (SIP core), IP core, or IP block is a reusable unit of logic, cell, or integrated circuit layout design that is the intellectual property of one party. IP cores can be licensed to another party or owned and used by a single party. The term comes from the licensing of the patent or source code copyright that exists in the design. Designers of application-specific integrated circuits (ASIC) and systems of field-programmable gate array (FPGA) logic can use IP cores as building blocks. History The licensing and use of IP cores in chip design came into common practice in the 1990s. There were many licensors and also many foundries competing on the market. In 2013, the most widely licensed IP cores are from Arm Holdings (43.2% market share), Synopsys Inc. (13.9% market share), Imagination Technologies (9% market share) and Cadence Design Systems (5.1% market share). Types of IP cores The use of an IP core in chip design is comparable to the use of a library for computer programming or a discrete integrated circuit component for printed circuit board design. Each is a reusable component of design logic with a defined interface and behavior that has been verified by its creator and is integrated into a larger design. Soft cores IP cores are commonly offered as synthesizable RTL in a hardware description language such as Verilog or VHDL. These are analogous to low-level languages such as C in the field of computer programming. IP cores delivered to chip designers as RTL permit chip designers to modify designs at the functional level, though many IP vendors offer no warranty or support for modified designs. IP cores are also sometimes offered as generic gate-level netlists. The netlist is a boolean-algebra representation of the IP's logical function implemented as generic gates or process-specific standard cells. An IP core implemented as generic gates can be compiled for any process technology. A gate-level netlist is analogous to an assembly code listing in the field of computer programming. A netlist gives the IP core vendor reasonable protection against reverse engineering. See also: integrated circuit layout design protection. Both netlist and synthesizable cores are called soft cores since both allow a synthesis, placement and routing (SPR) design flow. Hard cores Hard cores (or hard macros) are analog or digital IP cores whose function cannot be significantly modified by chip designers.