TXT (Text) records are part of the Domain Name System. They store different text of different reasons, some of it in computer code form, and some of it in human language form.
TXT files are typically used to check that you are indeed the domain’s owner and to keep your email address safe from spam and other threats. Whoever sold your domain to you keeps hold of your TXT records, so you’ll have to get in touch with them if you want to gain access. In fact, for that reason, it’s a good idea to check with the domain seller to make sure that they will give you access to your TXT records— before you buy.
You can write anything in a TXT record but bear in mind that you’ll want to put your words inside quotation marks, or each of them will be treated like a separate string. You should also think about the TTL (Time to Live) of the record, which sets how regularly it will be updated. With TXT you can use a variety of elements and standards like the DKIM. This standard (which stands for Domain Keys Identified Mail) can be added to your DNS records to create a domain key which encrypts your email headers. You can put the SPF record in the TXT section to validate your email address and avoid spam. There are more ways to use encryption with your TXT records so that your domain and email remain secure.