what does Coverage mean in sequencing?

[Pradhaun]

Hi folks,

I am new to genomics research. I have just started to explore the basics of genomics. I would appreciate if anybody can please explain to me about the term COVERAGE?
In most of the articles, I come across like 45X coverage or 30Xcoverage.
What does it implies?

Thank you,

Pradhaun

[swbarnes2]

It means that on average, each letter in the genome is covered, or contained in 45 different reads. Next-gen sequencing reads are more error-prone than, say, sanger reads. If you called a genotype bsaed on 3 different sanger reads covering that spot, that would be a pretty sure thing. If you only had 3 Illumina reads covering that spot, your call would be dicey. If you had 20, you'd be pretty confident.

[Pradhaun]

Thank you swbarnes2!

Thats a very clear explanation given by you. I appreciate that!
Now with this, I can read articles with proper understanding.

Again Thank you!

Pradhaun.