`PUT` and `PATCH` are both HTTP methods used for updating resources on the server, but they differ in their semantics and how they handle resource updates.
1. **PUT**:
- `PUT` is used to update a resource or create it if it doesn't exist.
- When you send a `PUT` request to a resource endpoint, you are replacing the entire resource with the new representation provided in the request payload.
- If the resource doesn't exist at the specified URI, `PUT` will typically create a new resource with that URI.
- `PUT` requests are idempotent, meaning that making the same request multiple times will have the same effect as making it once.
- In other words, when you use `PUT`, you're essentially saying, "Here is the complete representation of the resource, update it or create it if it doesn't exist."
2. **PATCH**:
- `PATCH` is used to apply partial modifications to a resource.
- When you send a `PATCH` request to a resource endpoint, you are only providing the changes that need to be applied to the resource, rather than the entire representation.
- `PATCH` requests are typically used when you want to update only certain fields of a resource without affecting the rest of its properties.
- `PATCH` requests are also idempotent, meaning that applying the same patch multiple times will result in the same final state.
- In summary, `PATCH` allows you to make partial updates to a resource, modifying only the specified fields.
In general, if you have all the data needed to update a resource, you can use `PUT` to send the entire new representation. If you only need to update specific fields of a resource, you can use `PATCH` to send a partial update.