Solidity provides the following reference types:
- Arrays: These are fixed as well as dynamic arrays. Details are given later in this chapter.
- Structs: These are custom, user-defined structures.
- String: This is sequence of characters. In Solidity, strings are eventually stored as bytes. Details are give later in this chapter.
- Mappings: This is similar to a hash table or dictionary in other languages storing key-value pairs.