Specs when buying new laptop batteries

[bushmins]

Ive been after a new battery for my laptop and have looked at many different website with many different prices.

The battery i have is 10.8V 2600mAh

How important is it that i get a new battery with the same rating of mAh (I have no idea what mAh is)

 

[hyster]

Its milliamps per hour, the higher the number, the longer the battery will last. It would also be bulkier and a bit heavier though.