There are 270 million domains registered to date, only a fraction are premium domains.
Domains are premium assest digital real estate. They give authority status and credibility. People searching for keywords will more likely choose a domain that is descriptive and will proceed it to be trustworthy.
Keyword domains have the advantage of ease to recall short name brands with less confusion.
It is not uncommon for premium domains to sell for 6 & 7 figures.
Domain names are like real estate, rather than having bricks and mortar you have a virtual property that is classed as a commodity.
Depending on how many words are used and what extenstions determines the price of your domain. The most sort after domains are the ones with one or two words or or 2 & 3 letters or numbers.
Most popular and valued tld (Top Level Domain) domain extentions are .com, .net, .org, followed by the increasingly popular .in and .cc.
Try to stick with words from the english dictionary although other countries domains and language are just as crucial.
Stick to short generic words or acronyms.