You may have people talking about four-point, five-point, and six-point harnesses, and what the ‘points’ refer to are the number of fixing points and therefore straps the harness has. A four-point harness is considered the entry level, comprising two shoulder straps, and two lap straps. However most people prefer to opt for either a five- or sixpoint harness, which incorporates either one or two crutch straps in addition to the shoulder and lap straps. These crutch straps prevent the driver from ‘submarining’ in the seat and falling out from under the harness.
The advantage of having more fixing points is simply because it spreads the load across the harness. For example a 100kg load spread over four fixing points is 25kg load per point, whereas 100kg load on a six-point harness is 16.7kgs per point. Therefore you can see that a six-point harness is capable of dealing with much higher loads than a four-point one.