In most cases, you will be required to carry an FR-44 for 3 years after a DUI conviction. In some cases, you may only be required to carry an SR-22, but the state of Florida changed their laws in 2007 to require everyone convicted of a DUI to have FR-44 for a minimum of 3 years.
Like the SR-22, an FR-44 is a certificate of compliance, not an actual insurance policy. It states that the person named on the form carries 10 times the liability coverage of the state minimum or $100k of coverage for every $10K required by law. This means that in addition to the FR-44, you are required to maintain an auto insurance policy that is much higher than other drivers.
In essence, an FR-44 is simply the form that must be filed which states you are carrying more insurance coverage. You are required to pay a monthly or annual fee for the certificate, and the insurance company then files it with the Department of Motor Vehicles. Failure to maintain an FR-44 can result in the suspension or revocation of your driving privilege.