There are 3 basic types of leases when it comes to commercial real estate. The gross, or full service, the lease is when the renter pays a gross sum per month, and the landlord pays expenses such as taxes, insurance, maintenance, etc. out of that amount. The renter pays nothing extra. The net lease is when the renter pays a smaller amount, but will also need to pay extra to cover added building expenses. The modified gross lease is a combination of the two, where the renter pays a smaller amount in rent, but usually must pay for maintenance or janitorial services on their own.