what is a cell?why is it important>?

I have to say,it's a big question。And I guess you didn't ask for clearly。Because cell could be used in biology,in database,or something else。
(我不得不说,你问的问题有点大。而且问的不是很清楚。因为cell这个单词在生物领域,数据库,还有其他领域都有不同的含义。)
And I guess here the cell is as biology word pointed。(我猜你这里是从生物的角度问的)
cell:(biology) the functional basic unit of life (cell这里是指细胞,生命中的最小功能基本单元)
Why is it important?
Because all the vital functions of an organism occur within cells。
（因为所有必需的生物有机体的功能作用都是在细胞内进行的）