Example
Before
User First Name shippingAddressLine OrderTotal
After
user_first_name shipping_address_line order_total
Where snake_case is used
snake_case is the convention for variables and functions in Python and Ruby, and for table and column names in most SQL databases.
CONSTANT_CASE
Many languages write constants in uppercase snake case, such as MAX_RETRIES. Convert to snake_case here, then run the result through the Uppercase converter.