Documents in MongoDB map directly to objects in your programming language. Modify your schema as your apps grow over time.

Sure, MongoDB is a NoSQL database that provides high performance, high availability, and easy scalability. It works on the concept of collections and documents.

A document in MongoDB is the same as a record in SQL databases. The MongoDB document can be easily mapped to programming language data types. The document structure in MongoDB is more in line with how developers construct their classes and objects in their respective programming languages. Developers often say that their classes are not rows and columns but have a clear structure with key-value pairs.

As your application grows over time, MongoDB allows you to modify your schema. Unlike SQL databases, where you have to define your schema before you can add data, MongoDB's dynamic schema allows you to add fields as you go. This can be particularly useful for agile development methodologies, where your data requirements might change as your application evolves.

Here are the steps to modify your schema in MongoDB:

1. Connect to your MongoDB instance.
2. Select the database and the collection you want to modify.
3. Use the $set operator to add new fields to documents.
4. Use the $unset operator to remove fields from documents.
5. Use the $rename operator to rename fields.

Remember, MongoDB does not require all documents in a collection to have the same schema. That means different documents in a collection can have different fields. This flexibility can be a powerful feature, but it should be used carefully to ensure data consistency.