All insurance companies charge higher rates for drivers with accidents or tickets on their records.  Insurance companies charge higher rates because statistics show that these drivers are higher risks.  Each company has different ratings, but they all adjust their rates to reflect their exposure.

Lets say,  you have an accident or a ticket, your policy will not increase until your renewal.  Thats why its best to have an annual policy.  If you have a 6 month policy and you receive a ticket or have an accident during that period you will be surcharged on renewal, (in this case, 6 months later).  If you had a 12 month policy you would not see an increase until the renewal, (12 months later).