Imagine if an infrastructure which is available and everyone can securely process transactional code and access the data that can never be tampered. All the transactions are stored in a form of a block which is very hard to manipulate or tamper once they are stored on a blockchain. This is the behavior of blockchain where you can store the data in the most trustworthy way in the scenarios where there is no trust. Blockchain obviously is not a place where you can store a large amount of data for every transaction. For e.g. you cannot store a lot of images or documents in bulk, but you can for sure store an information that can validate that your documents or images are tampered with or not.