What are the differences between SEO and SEM?

[pranav]

What are the differences between SEO and SEM?

[vinothjose]

SEO is the organic way of ranking.
SEM is the paid way of ranking

[Saravanan28]

SEO -
The term stands for Search Engine Optimization. Optimize your Website to be in SERP's as through Organic Search by following Search Engines SEO Guidelines.
SEM -
Search Engine Marketing worked under Paid Ad's which placed under Google, Bing, MSN as AD's with specific keywords and also known as Non-Organic Search.