SEO is Search engine optimization is the process of getting high traffic with organic and inorganic searches on the result page. It increases your website's position on search result pages. Notice this point high position websites listed more people can see it.

1. What is SEO, and how does it work?
SEO is Search engine optimization is the process of getting high traffic with
organic and inorganic searches on the result page. It increases your
website's position on search result pages. Notice this point high
position websites listed more people can see it.
Definition of SEO:
Make a perfect SEO that may involve activities.
Create relevant keywords to reach good search traffic.
To make high-quality related content to rank a search engine result page.
To increase relevant links that will increase traffic.
Google will analyze your measurable results.
How does SEO work for search engines:
Nowadays, Search engine company that has been developing to rank a
website are a factor that defines content and search. Most search engines
will decide on content Google will scan with crawl and index.
You should consist of two things they are.
1) Crawling:
Crawling is nothing, but it will discover a website search spiders will check all
relevant content on our website. Once you any irrelevant content, Google
will take a penalty on our website.
2) Indexing:
Indexing is content storing while creating new content next you want to on
your Index file. After indexing, it will crawl. So pages will enter a search
engine spam, block, duplicate page it will index.
Once you have crawling and indexing, Google will analyze
your pages in ranking factors.
1) Keywords
2) Mobile friendly
3) Backlinks profile
4) Speed
In this SEO, Most techniques are:
On-Page SEO
1) High-Quality content
2) Page titles and description
3) Page content
4) Header tags

2. 5) Content Formatting
6) image optimization
7) URL Optimization
8) Website Speed check
9) Internal and External links
Off-page SEO
1) Plagiarism-free content
2) Guest posting
3) Social media sharing
4) Social bookmarking
5) Article Submission
6) Forum Submission
7) Directory Submission
8) Questions and Answers
9) Video Submission
10) Infographics
11) Image sharing
12) Press release
13) Document sharing
This section SEO is mainly for ranking a website or those who
start a website or business its uses for your website.
Thanks for reading my answer.
Good luck