For non-unique user-provided attributes, Kubernetes provides [labels](/docs/user-guide/labels) and [annotations](/docs/concepts/overview/working-with-objects/annotations/).
See the [identifiers design doc](https://git.k8s.io/community/contributors/design-proposals/architecture/identifiers.md) for the precise syntax rules for Names and UIDs.
By convention, the names of Kubernetes resources should be up to maximum length of 253 characters and consist of lower case alphanumeric characters, `-`, and `.`, but certain resources have more specific restrictions.