Understanding and working with syllabus

Distribution of prominence. Location of stress within a word.
Languages differ in this respect. There is fixed and free (variable) word stress. Languages of the fixed stress type have stress predominantly on a given location in a word. Languages with variable stress enjoy more freedom for stress placement.
French, e.g., is a language where word stress is normally
fixed on the last syllable. The final syllable stress is an areal characteristic of Turkic languages, Iranian languages and the Armenian language. Other examples of fixed stress are Finnish and Czech, both with initial syllable stress, and Polish and Swahili, both with penultimate syllable stress.
A relatively small proportion of the languages of the world allow a range of different locations of stress: Dutch, English, Greek, Italian, Rumanian, Russian, Spanish etc. Here are some examples: English contact, re act, Russian правда, дopoгa, caмовар
Some authors say that in English word stress is free and fixed at the same time. It is fixed in the sense that you cannot change the position of syllable prominence in any given word at will. We have to observe the patterns that already exist. We cannot choose them according to the situation, style, etc. It is free in the sense that it can fall on any syllable.
Although word-stress in English is free, it is possible to talk about basic types of accentual patterns and about basic accentual tendencies. These two aspects are closely related, but should be kept separate. When we talk about tendencies, we are trying to discover the reasons why this or that accentual pattern has emerged into existence. There are semantic (recessive), retentive and rhythmic tendencies.
The semantic (recessive) tendency chooses the stressed syllable in the semantically predominant morpheme. This is usually the root morpheme of a word, e.g. decide, practical, etc.
The retentive tendency accounts for preserving stress on the same syllable in derivative words as in beauty-beautiful-beautufy; wonder-wonderfully.
The rhythmic tendency accounts for the appearance of a second stress in many English polysyllabic words. There is a tendency towards alternation between strong and weak syllables in speech and, in particular, within a word. This is why it is not common of English to have polysyllabic words with one stress only. Nevertheless, such words do exist: e.g. beautifully.

Rules for predicting stress are based on the morphological structure of words, i.e. they presuppose a classification of prefixes and suffixes into strong and weak according to their stress potential and it is also based on the classification of compound words according to the principles of their formation.

The attempts to work out rules that would enable a learner to predict a word stress pattern are very popular in the current phonetic science. It is part of generative phonology.
Degrees of stress
Phonetic prominence of a syllable in a word is relative, i.e. compared with the preceding one. But the speaker of a particular language is capable of categorizing the actual phonetic differences and distinguishing the phonologically relevant ones while ignoring those which are not relevant for word recognition. Much of stress perception is done as expected, that is in anticipation of regular rhythmic beats or in analogy with other similar words.
The English word indivisibility illustrates different degrees of syllable prominence with an identical vowel [i]. Phonetically,
there are, in fact, as many degrees of prominence as there are syllables in the word, namely, seven. However, phonologically, there are only three degrees: only one primary stress on bi, two secondary stresses - in, vi — and the rest of the syllables are termed as having a weak stress, which might also be called unstressed.
Some authors also distinguish tertiary stress, which is as weak as secondary but has a different distribution: it follows the primary stress, while the secondary stress precedes it. LPD defines tertiary stress as the location of a potential rhythmic beat either after the primary stress, or between the secondary and the primary (as in indivisibility). Tertiary stress is usually associated with American English words like laboratory ['l], territory ['t]'.
However, there are two generally accepted degrees of stress: primary and secondary. Is secondary stress relevant? Perhaps, it is only a phonetic feature significant only for observing the pronunciation norm. Perhaps it doesn't matter as far as the meaning of a word is concerned. It is difficult to provide examples of words where secondary stress alone would lead to a difference in meaning (e.g. to 'undertake - to under'take). All dictionaries
use the indication of secondary and primary stress which shows, obviously, that this is a constant and compulsory feature of English stress.
Primary and secondary stress are functionally different. We can see the difference clearly as soon as we touch upon the issue of the relationship between word stress and utterance stress. It will be seen that it is only the syllable carrying primary stress that is capable of becoming nuclear syllable on utterance level. We will see that it is not the pitch level that indicates the syllable as secondary or primary but its potential of becoming nuclear.