Layer 1

Why Trust Techopedia

What Does Layer 1 Mean?

Layer 1 is the first layer of the Open Systems Interconnect (OSI) Model. Layer 1 consists of the various networking hardware and transmission technologies being employed by networks.


This layer is the first and serves as the foundation, the fundamental layer underneath the logical data structures of other higher level network functions. This is considered as the most complex layer simply because of all the different hardware combinations there is possible.

Layer 1 is also known as the Physical Layer.

Techopedia Explains Layer 1

Layer 1 of the OSI layer refers to the physical media of the network which are the actual hardware components that process and transmit digital data across great distances.

It defines the means of transport for raw bits of data, actual electrical signals, rather than the logical data packets that other layers handle. Layer 1 provides the electrical, mechanical and procedural interface for the transmission medium.

Specified in this layer are the actual size and shapes of connectors and conduits, as well as the various modulation schemes and frequencies used for broadcasting.

Some of the major services performed by Layer 1:

  • Symbol-by-symbol or bit-by-bit delivery
  • Modulation
  • Circuit switching
  • Autonegotiation
  • Bit interleaving
  • Line Coding

Related Terms

Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.