Definition of Search Engine Optimization: SEO is a technique of making your website on top of SERP for a keyword entered by the user.

A search Engine works on four stages:
Crawling
Indexing
Calculating Relevancy:
Retrieving Results:
1.Crawling: A crawler comes to the website, collects all the data.
2.Indexing: Stores data as per categories {movies,fashion,travel etc}.
3.Calculating Relevancy: Ranking as per content, links, bold italics
4.Retrieving Results: Displays results on SERP.
SERP: Search Engine Results Page.
SERP Layout:Top 4 Ads->10 organic results->Bottom 3Ads

Important Places:
Title: It must be min 16 characters.
Description: Must be of 160 characters. (Install All in one SEO pack)
H1 to H4 headings: H1 heading cannot be repeated, H2 to H4 can be repeated.
Image alt: Giving an alternate text to the image because the crawler will not understand the images.
Bold& Italics: Highlight the important words in Bold or Italics because the crawler focuses on those words.
Filename: Your URL name is the filename, it should be properly named.
The First line of the paragraph: Crawler focuses on the first line of the paragraph, so make sure your write it well.
Links: Internal & Outbound links, crawler observes the links also, more the links more are the chances of coming on top of SERP. (Only relevant website links)
Keyword Research Techniques:
There are four keyword research techniques:
Brain Storming,

Google search/Suggest,

Keyword Planner,
Uber Suggest.

Black Hat Techniques:
Keyword stuffing
Changing font colors
Cloaking
Spammy Backlinks
EMD(Duplicate content)
Google Updates:
1.Panda Update
2.Penguin Update
3.EMD Update
4.Pigeon Update
5.Mobile-Friendly Update
6.Tob Heavy Update
7.Rank Brain
8.Free Update
For more information watch our Youtube Video :