[string.view.general]

The class template basic_string_view describes an object that can refer to a constant contiguous sequence of char-like ([strings.general]) objects with the first element of the sequence at position zero.

In the rest of [string.view], the type of the char-like objects held in a basic_string_view object is designated by charT.

[Note 1:

The library provides implicit conversions from const charT* and std::basic_string<charT, ..> to std::basic_string_view<charT, ..> so that user code can accept just std::basic_string_view<charT> as a non-templated parameter wherever a sequence of characters is expected.

User-defined types can define their own implicit conversions to std::basic_string_view<charT> in order to interoperate with these functions.

— end note]