Promoting encompasses a variety of activities designed to increase sales of singles and albums while they're charting.
Promoting can be done by individual Blockstars, entire bands and even Record Labels. Additionally, Social Media can be utilized by individual Blockstars to amplify or replace the promotion.
Just like with Concert Venues, Recording Studios and Record Labels, promotional activities range in effectiveness and cost on a scale of 1 to 10 - from handing out flyers on local college campuses all the way to a global TV ad campaign.
The effectiveness of Promoting is affected by a variety of Blockstar attributes, both Visible and Hidden, such as Promoting, Fame, Social Media and Charisma.
If a band is signed to a Record Label, then that label can also participate in the promotion. However, a Record Label can only promote one single or album at a time - so it will be up to the two players (i.e. the Record Label owner and the band manager) to reach agreement on the timing, duration and extent of the promotion. After all, a Record Label will have multiple bands at any given time that they need to support, and it can't support them all at the same time.