Looking on the internet deeply has found these results:

that is is the most popular phrase on the web.

binary sources have a less skewed 10 results on the web	that is 1135,000,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	That is her mother. After that we saw each other. 2. (used to indicate one of two or more persons, things, etc., already mentioned, referring to the one more�... English[edit]. Adverb[edit]. that is (not comparable). (conjunctive) In other words; that is to say. Used to introduce a clarification or explanation�... Used to introduce a noun clause that is usually the subject or object of a verb or a predicate nominative: "That contemporary American English is exuberantly�... Jan 21, 2015 ... C1 said when you want to give further details or be more exact about something: I 'll meet you in the city, that is, I will if the trains are running.

binary sources have a less skewed

10 results on the web

that is

1135,000,000 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

That is her mother. After that we saw each other. 2. (used to indicate one of two or more persons, things, etc., already mentioned, referring to the one more�...
English[edit]. Adverb[edit]. that is (not comparable). (conjunctive) In other words; that is to say. Used to introduce a clarification or explanation�...
Used to introduce a noun clause that is usually the subject or object of a verb or a predicate nominative: "That contemporary American English is exuberantly�...
Jan 21, 2015 ... C1 said when you want to give further details or be more exact about something: I 'll meet you in the city, that is, I will if the trains are running.