A field is the base equivalent of a spreadsheet column. Each field holds a particular category of information related to the record (row) in which it exists—for example, if you had records for each of a number of different items, you might have a field in which you store information about the price of each item.
Unlike in spreadsheets, each Airtable field can have a special field type for different kinds of rich content. There are many different field types, including file attachment, checkbox, phone number, long text, dropdown select, barcodes, and more! (For more specific information on all of the available field types, you can read the Field types article.)
Getting to the "Customize Fields" menu
You can add and customize fields, through the "Edit Table" menu. To get to the "Edit Table" menu, you can tap the dropdown arrow to the right of the name of the relevant table.
Alternatively, you can access the "Edit Table" menu by tapping the dropdown next to the title of the base (which will bring you to the "Edit Base" menu) scrolling down to the list of tables, and then tapping the table you wish to edit.
You can also get to the "Customize Fields" menu from within an expanded record, by tapping the title of the record at the top of the screen...
...Or by scrolling all the way to the bottom of an expanded record and tapping the blue "Customize Fields" button.
Tapping the "Customize Fields" button (however you decide to access it) will bring you to the blue "Customize Fields" menu. From here, you can change the field types and settings of existing fields, or add new fields. Note that editing the field settings or adding new fields within this menu will change the underlying "blueprints" for the entire base—that is to say, all fields for all views will be changed.
Editing a field
To edit an existing field, tap on its card. You'll be given a variety of customization options, depending on the type of field. When you're done customizing the field's settings, tap the "Save" button in the top right corner.
Adding a new field
To add a new field, tap the "Add a new field" button at the very bottom of the screen.
After naming your new field, you can select the appropriate field type by tapping on the "Field Type" button in the middle of the screen.
This will bring up a menu of all of the possible field types. Tap one of the icons to select that field type.
You can also move around a field on the customize fields menu by tapping and dragging on the hamburger icon on the right-hand side of the field you wish to move. Moving around a field like this will change the order in which the fields appear within the record. This can be useful for prioritizing certain fields over others.
Deleting a field
To delete a field, go into the edit field menu and tap the "Delete field" button at the bottom with the trashcan.