Safety standards are an essential part of auto racing.
Safety standards offer a required guaranty of basic protection to the various participants (drivers, crew, track personnel, rescue team...). Sanctioning bodies or specialized non-profit entities establish safety standards and the tests a product must undergo to earn their safety label. Such tests consist in timed flame exposure, applied pressure on a product or its components, resistance to various impact types from different angles… Samples of each product (according to size, options, etc.) are sent by the manufacturers to test laboratories approved by the sanctioning bodies, certification being granted if the given product exceeds the required standards. Here is a summary of the most commonly used and most stringent standards for the helmets:

The FIA standard was first made years back for Formula 1. The FIA standard for helmets has proven its use in amazing crashes and will be spread to many more series in the years to come, under FIA authority or not. Helmets labeled FIA go through SNELL resistance tests and even more violent tests. It implies a building of the shell in raw carbon and highly absorbing liner. All FIA helmets are made FHR homologated.
Standards & validity period
Where required

FIA: Used in Formula 1, GP2, GP3, WTCC, GT, WRC, WEC and other
top-level international categories.

More info
FIA 8859-2015 STANDARD
You will find herein all possible setups combinations FHR - tethers - post anchors – helmets, following the FIA 8859-2015 Frontal Head Restraint (FHR) standard.
For reading this matrix, you can either start from the FHR / thethers (on the left side of the matrix) or start from the helmet - post anchors (on the right side of the matrix), the arrows show that any combinations allowed on the left side can be used with any combinations allowed on the right side (and vice versa).
FIA 8860-2018 STANDARD
The latest FIA 8860-2018 standard subjects helmets to a range of violent impacts at varying angles and speeds, which they must withstand. This standard ensures that the equipment complies with a set of rigorous control points, to enhance the safety of the racing driver.

The FIA 8860-2018 standard is gradually being introduced in the various motorsport disciplines, but is already mandatory in Formula 1 in particular.

Below is a video of a crash implying one of our IVOS SNELL SA 2005 helmets with its explanations and the uninjured driver's testimony:

2. Seat breaks and there are multiple impacts on the helmet top resulting from violent contacts with roof and rollcage, as well as deformation of the shell basis on the FHR system
following crushing against the roof during the flips.
This last fact has prevented the driver's cervical vertebrae
from being wedged.

4. Shearing of the carbon by a metallic object (probably the door handle) which was stopped by the shell and the chin strap support.
A few words from Mr Neil Smith, driver of the car:
"I am certain that I am alive today thanks to a FHR Device and IVOS helmet supplied by Stand 21. I was lucky enough to be wearing them when another driver hit my left front wheel in a test session at Spa which snapped my steering, sending me into the armco at around 70-80mph followed by at least six rolls. I am amazed that I came out of it without any major injury, and very grateful to everyone at Stand 21 for their commitment to quality and safety."