The data is stored in the database. The following tables and columns represent the schema
[sts_WebForm](
[Guid] [uniqueidentifier] NOT NULL,
[ModuleId] [int] NOT NULL,
[ModuleGuid] [uniqueidentifier] NOT NULL,
[SiteGuid] [uniqueidentifier] NOT NULL,
[Name] [nvarchar](255) NOT NULL,
[Title] [nvarchar](255) NOT NULL,
[Instructions] [nvarchar](max) NULL,
[CompletedMessage] [nvarchar](max) NULL,
[CreatedUtc] [datetime] NOT NULL,
[CreatorId] [uniqueidentifier] NOT NULL,
[LastModifiedUtc] [datetime] NOT NULL,
[LastModifiedBy] [uniqueidentifier] NOT NULL,
[TotalPages] [int] NULL
represents the form instance
[sts_WebFormQuestion](
[Guid] [uniqueidentifier] NOT NULL,
[FormGuid] [uniqueidentifier] NOT NULL,
[QuestionTypeId] [int] NOT NULL,
[QuestionText] [nvarchar](max) NULL,
[IsRequired] [bit] NOT NULL,
[ValidationExpression] [nvarchar](max) NULL,
[InvalidMessage] [nvarchar](255) NULL,
[SortOrder] [int] NOT NULL,
[PageNumber] [int] NOT NULL,
[MinRange] [int] NOT NULL,
[MaxRange] [int] NOT NULL,
[CssClass] [nvarchar](100) NOT NULL,
[QuestionAlias] [nvarchar](max) NULL
represents questions on a form
[dbo].[sts_WebFormOption](
[Guid] [uniqueidentifier] NOT NULL,
[QuestionGuid] [uniqueidentifier] NOT NULL,
[OptionText] [nvarchar](255) NOT NULL,
[SortOrder] [int] NOT NULL,
[OptionValue] [nvarchar](255) NULL,
[OptionGroup] [nvarchar](255) NULL
represents options for list or multiple choice questions
[sts_WebFormResponseSet](
[Guid] [uniqueidentifier] NOT NULL,
[FormGuid] [uniqueidentifier] NOT NULL,
[UserGuid] [uniqueidentifier] NOT NULL,
[CreatedUtc] [datetime] NOT NULL,
[CreatedFromIP] [nvarchar](50) NULL,
[EmailTo] [nvarchar](255) NULL,
[UploadCount] [int] NULL,
[EmailToAlias] [nvarchar](255) NULL
represents a form submission
[sts_WebFormResponse](
[Guid] [uniqueidentifier] NOT NULL,
[ResponseSetGuid] [uniqueidentifier] NOT NULL,
[QuestionGuid] [uniqueidentifier] NOT NULL,
[Response] [nvarchar](max) NULL
represents a response to a specific question within a form submission
Hope that helps,
Joe