The standard analyzer is used by default for any full-text analyzed string field. If we were to reimplement the standard analyzer as a custom analyzer, it would be defined as follows:

{
    "type":      "custom",
    "tokenizer": "standard",
    "filter":  [ "lowercase", "stop" ]
}

In Normalizing Tokens and Stopwords: Performance Versus Precision, we talk about the lowercase, and stop token filters, but for the moment, let’s focus on the standard tokenizer.