To be able to break down the full understanding of chakras in a few basic paragraphs would be an utterly impossible task to do.
Being there are so many variables as to how one looks and percieves the entire functioning along with eaches own beliefs to the matter.
Variables go as far as to religious/spiritual beliefs, energy theory, Eastern model formation, Western model formation, new/old belief system, old sandscripts vs new sandscripts, different chakra number models, sound/vibration, elements and even meridians.
This can help provide a quick overall view to give one an overstanding of the most common chakra number model.
The newly common number model and well known in the Western (meaning Euro-American culture and also a certain percentage of modern Indian culture that obtain their information from the Euro-American cultural matrix.) is the 7 chakra model system.
Better known as the 7 Chakras, realistically only 6 chakras (or 6+1) chakras being that the 7th chakra Sahasrara (Sanskrit: सहस्रार, IAST: Sahasrāra, English: "thousand-petaled") or “Crown Chakra” technically cannot be pierced by Kuṇḍalinī in her ascent or descent. This model is typically learned/taught with the modern Western yogis.
🛑Just to note there is not just one or a few chakra systems in the original tradition, there are many!
The entire chakra system originated in India with the world’s oldest religion Hinduism according to many scholars. Strong practices, customs, and roots are dated to go as far back as 4,000 years or more. However, being that this age old religion doesn’t seem to have a specific founder it is quite difficult to have any accuracy on its origins and history. It’s uniqueness lies with the fact that it is not persay one single religion but in fact a compilation of many traditions and philosophies. Hinduism is also currently the third largest religion behind Islam and Christianity with about 900 million followers.
2300 B.C. and 1500 B.C. is around the time many scholars are to believe Hinduism was birthed into its existence. Inside the Indus Valley, and near modern-day Pakistan, but the argument among Hindus is that their faith is timeless and has always existed.
Hinduism is closely related to other Indian religions, including Sikhism, Jainism and Buddhism. Deriving into Buddhist tantric traditions, "Buddhist tantric traditions were strongly influenced at their inception by preexisting Śaiva Hindu traditions, but they also drew on a growing body of ritual and magical practices that had been developing for several centuries, since at least the 5th century ce, in Mahāyāna Buddhist circles."~Oxford Research University~
Even adding to other religions such as Christianity indicating in the book of Psalm 23. Swami Kriyananda explained that this Psalm is about the astral spine, and the process of the divine energy awakening within us. He mentioned that the “rod and staff” symbolize the spine itself, and the “cup runneth over” is about the kundalini, once re-united with the crown chakra, spilling abundantly over one’s whole being. When that union is permanently established, we are liberated and “dwell in the house of the Lord forever.
”Ultimately, all and every different chakra systems main purpose was to function as a template for nyāsa.
Meaning: the installation of mantras and deity-energies at specific points of the subtle body. This is a purpose that most people in todays day and age during practicing doesn’t seem to follow or gravitate towards anymore.
Spreading through the air such as energy does Qigong, an intriquete system of meditation and physical cultivation quite similar to yoga started to originate with Buddhism. Designed to help the practitioner achieve enlightenment, the awakening of one to one's true self.
“When Buddhism was transmitted to China, some of those practices were assimilated and eventually modified by the indigenous culture. The resulting transformation was the start of the Chinese Buddhist qigong tradition. Chinese Buddhist practice reaches a climax with the emergence of Chán (禪) Buddhism in the 7th century AD. Meditative practice was emphasized and a series of qigong exercises known as the Yijin Jing ("Muscle/Tendon Change Classic") was attributed to Bodhidharma. The Chinese martial arts community eventually identify this Yijing Jing as one of the secret training methods in Shaolin martial arts. Chinese martial arts practitioners, influenced by all the different elements within Chinese society, adapted and modified qigong theory with the goal of improving their fighting abilities. Many Chinese martial arts paid homage to Taoism or Buddhism by claiming them as their original source. For example, Tai chi chuan is often described as being Taoist in origin. Shaolin martial arts is named after the famous Buddhist Shaolin temple.”~History of Qigong~
The Mandarin Chinese term for the chakra system is Qi Gong. The energy flowing within one self is called Qi and this is the same energy that flows through channels. These number channels that run through the body are then called meridians.
Eastern medicine would then take a turn with traditional healing sciences. Tai Chi asserts that the body has natural patterns of qi energy associated with it. Disrupted, blockages, or unbalanced qi movements are seen to be the cause of the bodies current illnesses and therefore adding any additional symptoms.
Reiki masters would also work on energy blocks within the body by drawing on their own personal energy systems with the intention of healing different aspects of their life.
Adding the science of Acupuncture to also recognize the chakra systems or as it is called, the Taiji Pole, as the main energy conduit in the body. Over the years this practice has become an insurable medical practice in certain countries such as France.
A simple version of the 7 chakra model system is seen in a thirteenth-century postscriptural text called the Śāradā-tilaka. With its discovery it does in fact reconize there are a large number of existing chakra systems (such as systems of 12 or 16 chakras). In the 14th-15th Century Śiva-samhitā more elaborate versions of the same systems were found. Most yogis (both Indian and Western) are more familiar with the 7 chakra system teachings through Pūrṇānanda’s sixteenth-century work or John Woodroffe translations done in 1918, thus leaving this particular system to stay dominant for the last 4-5 Centuries.As Tantric Yoga matured (after the year 900 or so), every one of the many branches of the tradition articulated a different chakra system, and some branches articulated more than one. Five-chakra systems, six-chakra systems, seven, nine, ten, twelve, twenty-one and more chakras are taught, depending on what text and what lineage you’re looking at.
🛑Note: Tantric Buddhism older forms are often preserved in places such as Tibet and indeed the 5 Chakra system is dominant in that tradition (as well as the more fundamental three-bindu system).
Chakra (or padmas (lotuses), ādhāras, lakṣyas (focal points), Sanskrit: चक्र, IAST: cakra, Pali: cakka, lit. wheel, circle; English: /ˈtʃʌk-, ˈtʃækrə/ CHUK-, CHAK-rə .... etc.) comes from the tradition of Tantrik Yoga, which developed from 600-1300 CE, and is still alive today. Defined as a spinning disk or wheel of energy that runs along the spine of the human body. With the 7 chakra model there are 7 'main' chakras running along the spine, but also known to have as many as 114 all over the body.
Each chakra shares its own diety, element, organ connection, color, crystal, emotional connection, essential oil, sound vibration and a some additional other features. The Sanskrit alphabet is also distributed across the ‘petals’ in sound to all the chakras in the system.
•Specific Hindu deity or deities. (These are the templates for nyāsa.)
"In nyāsa (lit., ‘placing’), you visualize a specific mantric syllable in a specific location in a specific chakra in your energy body while silently intoning its sound.”~Hareesh.org~
Cause-deities (karana-devatās) are figures in every chakra system and form a fixed sequence from the lowest to the highest.
Ganesha (Sanskrit: गणेश, IAST: Gaṇeśa; listen (help·info)), also known as Ganapati, Vinayaka, or by numerous other names, is one of the best-known and most worshipped deities in the Hindu pantheon. His image is found throughout India, Nepal, Sri Lanka, Fiji, Thailand, Mauritius, Bali (Indonesia) and Bangladesh. Hindu denominations worship him regardless of affiliations. Devotion to Ganesha is widely diffused and extends to Jains and Buddhists.
(Optional depending on the chakra number system)
Brahma (Sanskrit: ब्रह्मा, IAST: Brahmā) is the creator god in Hinduism. He is also known as Svayambhu (self-born) or the creative aspect of Vishnu, Vāgīśa (Lord of Speech), and the creator of the four Vedas, one from each of his mouths. Brahma is consort of Gayatri and he is the father of Four Kumaras, Narada, Daksha, Marichi and many more.
Vishnu (/ˈvɪʃnuː/; Sanskrit pronunciation: [ʋɪʂɳʊ]; Sanskrit: विष्णु, IAST: Viṣṇu) is one of the principal deities of Hinduism. The "preserver" in the Hindu triad (Trimurti), Vishnu is revered as the supreme being In Vaishnavism as identical to the metaphysical concept of Brahman (Atman, the self, or unchanging ultimate reality), and is notable for adopting various incarnations (avatars such as Rama and Krishna) to preserve and protect dharmic principles whenever the world is threatened with evil, chaos, and destructive forces. In the Smarta Tradition of Hinduism Vishnu is also one of the five equivalent deities worshipped in Panchayatana puja.
Rudra (/ˈrʊdrə/; Sanskrit: रुद्र) is a Rigvedic deity, associated with wind or storm and the hunt. One translation of the name is "the roarer". In the Rigveda, Rudra has been praised as the "mightiest of the mighty". Rudra is the personification of 'terror'. Depending up on the periodic situation, Rudra can be meant as the most severe roarer/howler (could be a hurricane or tempest) or the most frightening one. The Shri Rudram hymn from the Yajurveda is dedicated to Rudra, and is important in the Saivism sect.
Ishvara (Sanskrit: ईश्वर, IAST: Īśvara) is a concept in Hinduism, with a wide range of meanings that depend on the era and the school of Hinduism. In ancient texts of Indian philosophy, depending on the context, Ishvara can mean supreme soul, ruler, lord, king, queen or husband. In medieval era Hindu texts, depending on the school of Hinduism, Ishvara means God, Supreme Being, personal god, or special Self.
In Shaivism and for many Hindus, Ishvara is synonymous with "Shiva", sometimes as Maheshvara or Parameshvara meaning the "Supreme lord", or as an Ishta-deva (personal god). Similarly for Vaishnavists and many Hindus, it is synonymous with Vishnu. In traditional Bhakti movements, Ishvara is one or more deities of an individual's preference from Hinduism's polytheistic canon of deities. In modern sectarian movements such as Arya Samaj and Brahmoism, Ishvara takes the form of a monotheistic God. In Yoga school of Hinduism, it is any "personal deity" or "spiritual inspiration".
Sadashiva (Sanskrit: सदाशिव, Sadāśiva, Tamil: சதாசிவம் ), is the Supreme Being Lord Parashivam in the Mantra marga Siddhanta sect of Shaivism. Sadasiva is the omnipotent, subtle, luminous absolute. The highest manifestation of almighty who is blessing with Anugrahaor grace, the fifth of Panchakritya - "Holy five acts" of Shiva. Sadasiva is usually depicted having five faces and ten hands, is also considered as one of the 25 Maheshwara murtams of Lord Shiva. Sivagamas conclude, Shiva Lingam, especially Mukhalingam, is another form of Sadasiva 
Bhairava (Maha Kala Bhairava)(Sanskrit: भैरव, lit. frightful) is a Hindu Tantric deity worshiped by Hindus. In Shaivism, he is a fierce manifestation of Shiva associated with annihilation. In Trika system Bhairavarepresents Supreme Reality, synonymous to Para Brahman. Generally in Hinduism, Bhairava is also called Dandapani (as he holds a rod or Danda to punish sinners) and Swaswa meaning "whose horse is a dog". In Vajrayana Buddhism, he is considered a fierce emanation of boddhisatva Mañjuśrī and also called Heruka, Vajrabhairava and Yamantaka.
(Optional depending on the chakra number system)