Unicode was introduced with the promise to tidy up most character issues present in older plain text encodng. The Unicode standard is a major achievement. It not only maps nearly every written glyph unto a unique number, it also defines the notions of upper case and lower case intelligently, and it defines types of characters, such as letters, numerals, punctuation, and much more. Associated with Unicode are several encodings to map the unique numbers to streams of bits in efficient ways.
In today’s world, UTF8 is very common, and especially suited to Western languages, because it coincides with ASCII for the ASCII characters. Other encodings are UTF16 and UTF32.
Unicode text is a preferred format under the Plain text file type.