A string stores text.

string name = "Player";

Interpolation:

Debug.Log($"{name} has {health} health");

Useful methods:

text.Length
text.ToUpper()
text.ToLower()
text.Contains("word")
text.StartsWith("save")
text.EndsWith(".json")
text.Replace("old", "new")
text.Split(',')
text.Trim()

Check empty text:

string.IsNullOrEmpty(text)