Which word identifies the kind of sentence that contains the main idea?

Why do people live together and form societies

Check my grammar: dear mr. peter szulczewskisubject: loyal customer’s complainti visited wish.com last month and found a 2-terabyte hard drive for only $69.99, an alive aquarium piranha fish for $7.99 and an unlocked samsung galaxy s9 phone for $599.99. the price of such quality item got me to buy all three of them thinking it is exactly what the description and pictures shows it be.the items arrived today and i am for giving me an actual samsung galaxy s9 for a low price but i got lied about the two other items, i know it doesn't always happen but we are losing our trust everytime it happens. i got 500gb hard drive and a plastic sardine fish. i thought i saved money but a 500-gigabyte hard drive should only be worth $40 and i am ok that they gave me a plastic fish because it is only $8 but they gave me a sardine plastic fish which is a very uninteresting species of fish and i have no use for it. you again for the phone. i like buying in your website and admire the prices you give to your items. i will not ask for a refund for the fish and hard drive but you should tell your sellers to use a truthful descriptions of their products because if they keep deceiving us, you might lose a lot of loyal customers.sincerely,russell john javierloyal customer

Use any method to combine the following sentences into one sentence. elvis presley died in 1977. his music is still popular today. graceland in memphis was his home.