Normally if you own a life insurance policy, the death benefit proceeds are included in your taxable estate. Depending on your financial situation this may or may not create a taxable estate for you. With estate tax rates topping out at 45%, it is certainly worth considering some options to avoid having your family pay taxes on those insurance proceeds.
One option is to have the insurance policy owned by an irrevocable trust (sometimes called an irrevocable life insurance trust or "ILIT"). Properly structured, you can provide a mechanism to pass those insurance proceeds to your intended beneficiaries and not included in your taxable estate. There are different rules if it is an existing policy versus whether you are purchasing a policy.
However, the downside with an ILIT is that it is irrevocable...you can't change the trust. Generally speaking with estate taxes, the more control and "strings" you control over an asset the more likely it will be included in your taxable estate. Thus, by cutting your control, you potentially remove it from your estate. By being irrevocable, you can't change the beneficiaries or pull the funds out of the trust. Like everything else in life, there are "give and takes".
There are methods in enabling the policy to be transferred to a new trust, but there are costs and hoops to jump through and should not be counted on as a sure thing.
In summary, use of an ILIT gives a person an easy step to save in estate taxes and provide for the same beneficiaries, so long as the strings are cut.