Most Layer field types are Text field data. This is a line of text without any formatting properties and is helpful to store any kind of data that can be a combination of letters, numbers, and special characters.
One thing to note is that when sorting by Text fields, numbers will be sorted as text. This means that 1, 11, 12, 13, 2, 21, 22, 23 are in alphabetical order. If you have sequential numbers, you’ll need to use leading 0’s to sort: 01, 02, 03, …10, 11, 12 etc.