"Session beer" is perfectly descriptive of the style: It's a beer that you can drink several of in one sitting – that is, without having to be wheeled out of the room. There are no hard and fast rules as to what makes a beer sessionable, but in general these are low alcohol (less than 5%), less bitter, and relatively low-calorie pale ales.
Bitter American, from San-Francisco-based 21st Amendment, perfects the session – by making a drinkable, no-frills beer that is all about the balance. It's labeled "Extra Pale Ale" on the ornate can (the company has the best can art in the craft beer kingdom, as styled by designer Joe Wilson), but the brewery's founders Shaun O'Sullivan and Nico Freccia have also called it a "session IPA," which gives a better indication of what they're up to here. The beer comes in at a relatively spry 4.5% alcohol, but they're still squeezing quite a bit of hop character into the pale golden brew. There is a distinctly citrusy, piney-ness to the aroma, and plenty of grapefruit hop flavor as well. In keeping with its low alcohol content, the beer is light-bodied and dry, but there's just enough of a cracker malt taste to keep the whole affair balanced.
We recently enjoyed a few on tap at a local bar, but this beer is almost better in its monkey-astronaut can. Have one while mowing the lawn or gardening, and then another one while you light up the grill before you invite some friends over to enjoy a few more with some burgers and dogs off that grill. [21st-amendment.com]