Early Guide on Setting Up a Host Profile Part 6
Subject areas are drawn from the tags posted on steem. Their usage on steemhost.com once again relates to the advertising feature. Advertisers may decide they want to target their advertising to specific categories (eg writing, photography etc.) Hosts who specify that they regularly write in that category will be notified that that an advertiser is offering to post an advertisement on their site. The host can elect to accept the advertisement or not. For instance the @dollarvigilante may want to advertise Anarchapulco on steemhost.com (yes Hosts have control over their own advertisements). He could specify that he would like to limit his advertisements to those who commonly are interested in and write about bitcoin. Perhaps @eljose27 never posts about bitcoin and is uninterested in it. Without having bitcoin as a subject area that he would write about, he would not receive notification about the advertisement.
BTW The advertiser has final say about who receive the advertisement. Sorry Pepsi ... Coca Cola won't be advertising on your page.
This is definitely going to be a great thing on this platform. Hoping for success of this initiative.