(NEXSTAR) — Your bread is speaking in code — or at least the colored tag or twist tie keeping its plastic bag is. While this isn’t exactly a science, it turns out that colors of the tags or twists serve a very specific purpose: to indicate the age of the bread.

And while this isn’t an exact science (and many stores/bakeries may have their own color systems), what follows is the generally accepted color code to indicate what day of the week a particular loaf was baked on.

Here is the most common color coding system:

• Monday — Blue
• Tuesday — Green
• Thursday — Red
• Friday — White
• Saturday — Yellow

In case you’re wondering where Wednesday and Sunday are in the list, well, those days are generally skipped for baking, according to fact-checking outlet Snopes. While origins of the color coding seem to be unknown, Snopes verified through research that many bakeries and stores do in fact use it. In conversation with Southern Living, Harry Peemoeller, senior instructor of Bakery and Bread Studies at Johnson & Wales University in Charlotte, North Carolina, also confirmed use of the system (though he also noted some exceptions).

Over the past few months, the “hack” has made the rounds on TikTok — with the information surprising many (or with others saying they always knew this).

“Did y’all know this?!” exclaimed TikToker mrtalkboxofficial in July. The video, which has around 57,000 likes and over 1 million views, was met with shock and some skepticism in the comments.

Some wondered why anyone would go through the trouble of deciphering an unreliable system when you could just peruse the Sell By date, which is also printed on the tag (or else, printed on the bag).

Which is actually an excellent point.

As previously mentioned, not all stores use the same tagging system or color code. Additionally, some stores might also make breads on Wednesdays and Sundays, further complicating the flow. Generally, the coding system isn’t meant to help customers but to help stores cycle through product before it goes bad.

As explained by Snopes, customers will also usually only encounter two color tags at a time, since stores replenish bread regularly (or at least they should).

All-in-all, using the Sell By date is a bread buyer’s best bet.