TXT are so-called plain text files, so simple text. Normally these are sequential strings of representable characters. Control characters are used for structuring. Mostly an ASCII or Unicode encoding is used. Such documents can be opened and viewed by any word processing program or text editor. Even a browser is able to display such files.
However, it should be noted that very simple as well as slightly older text editors may not be able to handle all encodings and thus, for example, German umlauts encoded in UTF-8 can not display properly.
It is also important, for example, that texts are generated for web pages in the coding, which should later also use the website.
Most often resolving problems with opening TXT files is very simple. Just install an appropriate program that supports such files. All of the listed programs support TXT files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of TXT files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate TXT files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Apple TextEdit applications is not on the list, select "Browse" option in order to manually locate the directory where Apple TextEdit has been installed.
Sometimes problems with opening TXT files may not lie with the application itself, but can arise due to other causes, such as: