Suppose i_E , i_C , and i_B denote the emitter current, the...

In a transistor, the emitter current $i_E$ is the sum of the base current $i_B$ and the collector current $i_C$.

$i_E = i_B + i_C$

The base region is very thin and lightly doped, so only a very small fraction of the charge carriers from the emitter recombine in the base. Thus, the base current $i_B$ is very small, typically about $1\%$ to $5\%$ of the emitter current $i_E$.

Therefore, $i_B$ is much smaller than $i_E$.

Since $i_C = i_E - i_B$ and $i_B$ is a small positive value, the collector current $i_C$ is slightly smaller than the emitter current $i_E$.