# What is the role of this word?

**URL:** <https://discourse.julialang.org/t/what-is-the-role-of-this-word/107704>\
**Category:** New to Julia\
**Created:** [December 16, 2023, 10:05am UTC](https://discourse.julialang.org/t/what-is-the-role-of-this-word/107704 "2023-12-16T10:05:06Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![hlbnet](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hlbnet/32/204549_2.png) [@hlbnet](https://discourse.julialang.org/u/hlbnet)\
**Post date:** [December 16, 2023, 10:05am UTC](https://discourse.julialang.org/t/what-is-the-role-of-this-word/107704/1 "2023-12-16T10:05:07Z")

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Hello,  
I am very new to Julia.  
Browsing Julia code implementation, I can see the following construct:

```julia
"""
    Some comments here ...
"""
Foo
...

```

My question is about this single word, here Foo, that is alone on a line. What is the role of it ? Is it a variable declaration with no type and no value ? Is it a type declaration (seems to be, but I expected struct or mutable struct or abstract type) ? Is it just documentation ? Or else ? What if we remove or change it, will it affect the execution ?

Here, a real example from a file string.jl :

```julia
"""
    String <: AbstractString

The default string type in Julia, used by e.g. string literals.

`String`s are immutable sequences of `Char`s. A `String` is stored internally as
a contiguous byte array, and while they are interpreted as being UTF-8 encoded,
they can be composed of any byte sequence. Use [`isvalid`](@ref) to validate
that the underlying byte sequence is valid as UTF-8.
"""
String

```

---

<div class="post-metadata">

**Author:** ![jules](https://avatars.discourse-cdn.com/v4/letter/j/41988e/32.png) [@jules](https://discourse.julialang.org/u/jules)\
**Post date:** [December 16, 2023, 10:21am UTC](https://discourse.julialang.org/t/what-is-the-role-of-this-word/107704/2 "2023-12-16T10:21:04Z")

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It’s just a target for the docstring. Sometimes people separate struct/function definitions and docstrings. Maybe String is defined in an unusual way somewhere else, for example in C code because it’s such a fundamental type, I haven’t checked.

---

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**Author:** ![Benny](https://avatars.discourse-cdn.com/v4/letter/b/49beb7/32.png) [@Benny](https://discourse.julialang.org/u/Benny)\
**Post date:** [December 16, 2023, 9:49pm UTC](https://discourse.julialang.org/t/what-is-the-role-of-this-word/107704/3 "2023-12-16T21:49:11Z")

</div>

> [@jules](#):
>
> Maybe String is defined in an unusual way somewhere else, for example in C code

That’s generally the case for `Core` types, you can check with `parentmodule(_type)`.