What are threads?

The site that allows you to create new topics of conversation is called a forum. The newly created topic of conversation is called a thread, each separated entry is called a post. The person making the entry is called a poster. The post contains alphanumerical characters that are arranged in certain order to make logical sense, by either a human reader or a computer who interpret them as links to external sites containing any kind of audiovisual or text content. The alphanumerical characters belong to an alphabet, thus the post can be made in many languages, but in this particular forum, the predominant language is English.

The English language is present worldwide, though the major countries that speak them natively are England and its surroundings, The united States and Australia.

The countries are a delimited land and sea territory in the planet earth.

The planet earth is the third planet of the solar system.

The solar system, as the name suggest, contains a star at the center.

The star of the solar system is just one of the estimated 100 billion stars of the milky way.

The milky way is a big group of stars that orbit a black hole.

Sorry, what was the question again?

@Alientcp I think you lost the thread there.

Aint it weird how meanings change?

When i was a kid threads meant nice clothes.

@Thalassokrator said in #5:

@MIHIR_KATTI
That's what dictionaries and thesauri are for:
www.merriam-webster.com/dictionary/thread
or
en.wiktionary.org/wiki/thread

Observations about a word can help you find its correct meaning in a dictionary in a timely manner. It probably will take you longer to read this post than it would have taken you to look it up in a dictionary yourself.

In this case you have already observed that people are talking about "this thread" or "that thread". So you know it's probably a noun and NOT a verb or an adjective. You can rule out the verb "to thread" based on the usage you observed. Then you go through the different meanings of the noun one by one to find the one that fits:

I have always assumed that people are calling them "threads" because they are linear (one response after the other) and soon become very long, just like a literal filament or a thread of fibres.

On a related note, many people on the lichess forum confuse the word "thread" with the word "forum". Their meaning is not the same:
Forum derives from the Latin name for the central public marketplace that was always present in a typical ancient Roman city. The one in the city of Rome itself is most famous of course:
en.wikipedia.org/wiki/Roman_Forum

Nowadays people usually use this word metaphorically to mean a place for conversation and discussion: the proverbial "marketplace of ideas". That's how the internet forum got its name.

So to recap:
We're writing messages and responses in a thread (responding to your original post). All of that is happening in the marketplace of ideas that is the internet forum. Hosted on lichess in this particular case.
And we can share ideas in mere seconds from all over the world. Isn't that great?
@Thalassokrator, so if I post a message(like I did with this topic), then if everyone posted it, then that is called a thread?

@MIHIR_KATTI said in #24:

@Thalassokrator, so if I post a message(like I did with this topic), then if everyone posted it, then that is called a thread?

If you go to forum --> off-topic, you are going to see something like this.

What are threads?
Israel vs palestine
I proved that circles don't exist.
First person on lichess?
What are your phobias? pt.2 (I losg the other part)
how to turn a video into a short on youtube

Each one of those being a link to a separated conversation. Each one of those are a separated topics, or threads.
It does not matter if people respond to them or not, once created they are a thread . And the responses inside are called posts.