Most interesting apps show and capture data. Traditionally, apps built by software developers use proprietary mechanisms to store data in structured databases. AppSheet avoids this approach for two reasons: (1) our app creators are not software developers, (2) we want our app creators to be in full control of their data.
Instead AppSheet apps use data from spreadsheets. Spreadsheets allow almost anyone to organize and store data. In later sections, we'll describe how you can also access data from other sources, but for now, let's focus on spreadsheets.
AppSheet cannot access data from a spreadsheet on your PC, but it can access data from a spreadsheet stored in a cloud file system like Google Drive or Dropbox. To explain it really simply, AppSheet makes your cloud-hosted spreadsheet behave like a simple database. The power of using a cloud-hosted spreadsheet is that there are no copies of your data created, nor is the data 'uploaded' into AppSheet servers. Instead, AppSheet reads and writes directly to your spreadsheet.
AppSheet automatically infers the structure of your data from the spreadsheet you provide. AppSheet models a data set as a 'table'-- i.e. a collection of rows with uniformly structured columns. Each spreadsheet is treated as a single 'table'.
For each column, AppSheet infers a data type, such as text, number, date, etc. There are more than 20 data types recognized. AppSheet also automatically groups related columns to form composite columns-- eg: [FirstName and LastName], or [Street, City, State]. These inferences happen automatically but of course, they may not always make the right decision, so you can always override and fine tune these choices.