What are snippets in Shopify themes?

Snippets are a crucial feature in Shopify themes that promote efficiency and modularity in theme development. They allow developers to create reusable code components that can be included and shared across various parts of a theme. This modular approach means that developers can write code once in a snippet and include it wherever needed without having to duplicate the same code, making the overall theme easier to maintain and update.

Using snippets streamlines the development process, as changes made to a snippet automatically apply wherever the snippet is used throughout the theme. This not only saves time but also reduces the potential for errors that can arise from having multiple versions of the same code in different places.

In contrast, the other choices do not accurately describe snippets. External JavaScript libraries pertain to adding functionality via scripts, while templates for product listings are more connected to the individual layout and presentation of products, and images used across themes do not align with the concept of code modularity.