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What is meant by least/most significant byte of the value?

Regarding for example " * Little-endian: A little-endian system first stores the least significant byte of the value, followed by the most significant byte."

What does this “significance” mean?


Course: Deep Dive into the Internals of the Database - Learn Interactively
Lesson: Binary Encoding of Data Types

Hi @Dmitry_Polovinkin
In the context of computing and data storage, the term “significant” refers to the importance or weight of a particular part within a larger structure, such as a multibyte value.

Whereas, the terms “least significant byte” (LSB) and “most significant byte” (MSB) refer to the order in which bytes are stored in memory for multibyte values like integers.

  • Least Significant Byte (LSB): It is the byte that holds the least significant part of a multibyte value. In a little-endian system, the least significant byte is stored first, meaning it has the lowest memory address.
  • Most Significant Byte (MSB): It is the byte that holds the most significant part of a multibyte value. In a little-endian system, the most significant byte is stored last, meaning it has the highest memory address.

Here’s a breakdown:

Little-Endian Storage Order: LSB first, followed by the next byte, and so on, with MSB stored last.

Big-Endian Storage Order: MSB first, followed by the next byte, and so on, with LSB stored last.

In the given example, for the binary representation of a numeric value, the least significant byte contains the bits that contribute the least to the overall value, and the most significant byte contains the bits that contribute the most. The choice of endianness affects how these bytes are arranged in memory.

For example, let’s consider the 32-bit integer value 0x12345678:

  • Little-Endian (LSB first): 78 56 34 12
  • Big-Endian (MSB first): 12 34 56 78

In little-endian, the least significant byte 0x78 is stored at the lowest memory address, and the most significant byte 0x12 is stored at the highest memory address. In big-endian, it’s the opposite. The significance here refers to the contribution of each byte to the overall numeric value.

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thanks!!

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