Phonology is a branch of linguistics concerned with the systematic organization of sounds in languages. It has traditionally focused largely on the study of the systems of phonemes in particular languages (and therefore used to be also called phonemics, or phonematics), but it may also cover any linguistic analysis either at a level beneath the word (including syllable, onset and rime, articulatory gestures, articulatory features, mora, etc.) or at all levels of language where sound is considered to be structured for conveying linguistic meaning. Phonology also includes the study of equivalent organizational systems in sign languages. 

The word phonology (as in the phonology of English) can also refer to the phonological system (sound system) of a given language. This is one of the fundamental systems which a language is considered to comprise, like its syntax and its vocabulary. 

Phonology is often distinguished from phonetics. While phonetics concerns the physical production, acoustic transmission and perception of the sounds of speech, phonology describes the way sounds function within a given language or across languages to encode meaning. For many linguists, phonetics belongs to descriptive linguistics, and phonology to theoretical linguistics, although establishing the phonological system of a language is necessarily an application of theoretical principles to analysis of phonetic evidence. Note that this distinction was not always made, particularly before the development of the modern concept of the phoneme in the mid 20th century. Some subfields of modern phonology have a crossover with phonetics in descriptive disciplines such as psycholinguistics and speech perception, resulting in specific areas like articulatory phonology or laboratory phonology.

Now, provide a numbered list of answers to these questions:

1. When was the concept of the phoneme put forth?
2. Does phonology usually focus on phonemes is certain languages?
3. Did phonology have a different name at one point?
4. More than one?
5. What is one of those names?
6. And the other name?
7. Is phonology commonly differentiated from something?
8. From what?
9. How many concepts does phonetics concern?
10. And one of those concepts is?
11. And another one?
12. And the last one?
13. According to people who work in the field to which brand of linguistics does phonetics belong to?
14. And does phonology belong to a specific one?
15. Which one?
16. What is a person called who works in this field?
17. Can sign languages fall under this field in linguistics?
18. Under what branch specifically?
19. Can a sound system be considered part of a fundamental system of a language?

Numbered answers:
1. the mid 20th century.
2. yes
3. yes
4. yes
5. phonematics
6. phonemics
7. yes
8. phonetics
9. Three
10. physical production of the sounds of speech
11. the acoustic transmission of those sounds
12. The perception of the sounds
13. descriptive linguistics
14. yes
15. theoretical linguistics
16. linguist
17. yes
18. Phonology
19. yes