The Linux Standard Base (LSB) was a joint project by several Linux distributions under the organizational structure of the Linux Foundation to standardize the software system structure, including the Filesystem Hierarchy Standard. LSB was based on the POSIX specification, the Single UNIX Specification (SUS), and several other open standards, but extended them in certain areas.

According to LSB:

The goal of the LSB is to develop and promote a set of open standards that will increase compatibility among Linux distributions and enable software applications to run on any compliant system even in binary form. In addition, the LSB will help coordinate efforts to recruit software vendors to port and write products for Linux Operating Systems.

LSB compliance might be certified for a product by a certification procedure.

LSB specified standard libraries (centered around the ld-lsb.so), a number of commands and utilities that extend the POSIX standard, the layout of the file system hierarchy, run levels, the printing system, including spoolers such as CUPS and tools like Foomatic, and several extensions to the X Window System. It also specified boot facilities, such as $local_fs, $network, which were used to indicate service dependencies in System V-style initialization scripts. A machine readable comment block at the top of a script provided the information necessary to determine at which point of the initialization process the script should be invoked; it was called the LSB header.

The command lsb_release -a was available in many systems to get the LSB version details, or could be made available by installing an appropriate package, for example the redhat-lsb package in Red-Hat-flavored distributions such as Fedora, or the lsb-release package in Debian-based distributions.

The standard stopped being updated in 2015 and current Linux distributions do not adhere to or offer it; however, the lsb_release command is sometimes still available. On February 7, 2023, a former maintainer of the LSB wrote, "The LSB project is essentially abandoned."