The terminology gets a little confusing here, so one of the key points to know is that the green card represents your visa, so how long it lasts is the same as a green card, because it’s a visa for permanent residence. The green card itself lasts for 10 years and then will need to be renewed. As long as you continue to renew it and do not commit any crimes, you will be able to use it indefinitely and until you receive citizenship.
Once you have received your green card, you can plan to apply for citizenship at the five year mark. While that is an entirely new application, it is an easy-to-complete, single page application. Along with this form, you’ll submit proof that you have been a good citizen and that you have no criminal record.
At present, it takes approximately one year to 18 months to be approved for citizenship. You will need to complete an interview and a citizenship test; once both of these have been passed, you will give your oath of allegiance and receive your certificate of citizenship.