diff --git a/process/process_linux.go b/process/process_linux.go
index 3899c92..ae30041 100644
--- a/process/process_linux.go
+++ b/process/process_linux.go
@@ -56,6 +56,7 @@ type MemoryMapsStat struct {
 	Swap         uint64 `json:"swap"`
 }
 
+// String returns JSON value of the process.
 func (m MemoryMapsStat) String() string {
 	s, _ := json.Marshal(m)
 	return string(s)
@@ -74,6 +75,7 @@ func NewProcess(pid int32) (*Process, error) {
 	return p, err
 }
 
+// Ppid returns Parent Process ID of the process.
 func (p *Process) Ppid() (int32, error) {
 	_, ppid, _, _, _, err := p.fillFromStat()
 	if err != nil {
@@ -81,6 +83,8 @@ func (p *Process) Ppid() (int32, error) {
 	}
 	return ppid, nil
 }
+
+// Name returns name of the process.
 func (p *Process) Name() (string, error) {
 	if p.name == "" {
 		if err := p.fillFromStatus(); err != nil {
@@ -89,6 +93,8 @@ func (p *Process) Name() (string, error) {
 	}
 	return p.name, nil
 }
+
+// Exe returns executable path of the process.
 func (p *Process) Exe() (string, error) {
 	return p.fillFromExe()
 }
@@ -105,6 +111,7 @@ func (p *Process) CmdlineSlice() ([]string, error) {
 	return p.fillSliceFromCmdline()
 }
 
+// CreateTime returns created time of the process in seconds since the epoch, in UTC.
 func (p *Process) CreateTime() (int64, error) {
 	_, _, _, createTime, _, err := p.fillFromStat()
 	if err != nil {
@@ -113,9 +120,12 @@ func (p *Process) CreateTime() (int64, error) {
 	return createTime, nil
 }
 
+// Cwd returns current working directory of the process.
 func (p *Process) Cwd() (string, error) {
 	return p.fillFromCwd()
 }
+
+// Parent returns parent Process of the process.
 func (p *Process) Parent() (*Process, error) {
 	err := p.fillFromStatus()
 	if err != nil {
@@ -127,7 +137,7 @@ func (p *Process) Parent() (*Process, error) {
 	return NewProcess(p.parent)
 }
 
-// Status returnes the process status.
+// Status returns the process status.
 // Return value could be one of these.
 // R: Running S: Sleep T: Stop I: Idle
 // Z: Zombie W: Wait L: Lock
@@ -139,6 +149,8 @@ func (p *Process) Status() (string, error) {
 	}
 	return p.status, nil
 }
+
+// Uids returns user ids of the process as a slice of the int
 func (p *Process) Uids() ([]int32, error) {
 	err := p.fillFromStatus()
 	if err != nil {
@@ -146,6 +158,8 @@ func (p *Process) Uids() ([]int32, error) {
 	}
 	return p.uids, nil
 }
+
+// Gids returns group ids of the process as a slice of the int
 func (p *Process) Gids() ([]int32, error) {
 	err := p.fillFromStatus()
 	if err != nil {
@@ -153,6 +167,8 @@ func (p *Process) Gids() ([]int32, error) {
 	}
 	return p.gids, nil
 }
+
+// Terminal returns a terminal which is associated with the process.
 func (p *Process) Terminal() (string, error) {
 	terminal, _, _, _, _, err := p.fillFromStat()
 	if err != nil {
@@ -160,6 +176,9 @@ func (p *Process) Terminal() (string, error) {
 	}
 	return terminal, nil
 }
+
+// Nice returns a nice value (priority).
+// Notice: gopsutil can not set nice value.
 func (p *Process) Nice() (int32, error) {
 	_, _, _, _, nice, err := p.fillFromStat()
 	if err != nil {
@@ -167,15 +186,23 @@ func (p *Process) Nice() (int32, error) {
 	}
 	return nice, nil
 }
+
+// IOnice returns process I/O nice value (priority).
 func (p *Process) IOnice() (int32, error) {
 	return 0, common.ErrNotImplementedError
 }
+
+// Rlimit returns Resource Limits.
 func (p *Process) Rlimit() ([]RlimitStat, error) {
 	return nil, common.ErrNotImplementedError
 }
+
+// IOCounters returns IO Counters.
 func (p *Process) IOCounters() (*IOCountersStat, error) {
 	return p.fillFromIO()
 }
+
+// NumCtxSwitches returns the number of the context switches of the process.
 func (p *Process) NumCtxSwitches() (*NumCtxSwitchesStat, error) {
 	err := p.fillFromStatus()
 	if err != nil {
@@ -183,10 +210,14 @@ func (p *Process) NumCtxSwitches() (*NumCtxSwitchesStat, error) {
 	}
 	return p.numCtxSwitches, nil
 }
+
+// NumFDs returns the number of File Descriptors used by the process.
 func (p *Process) NumFDs() (int32, error) {
 	numFds, _, err := p.fillFromfd()
 	return numFds, err
 }
+
+// NumThreads returns the number of threads used by the process.
 func (p *Process) NumThreads() (int32, error) {
 	err := p.fillFromStatus()
 	if err != nil {
@@ -194,10 +225,16 @@ func (p *Process) NumThreads() (int32, error) {
 	}
 	return p.numThreads, nil
 }
+
+// Threads returns a map of threads
+//
+// Notice: Not implemented yet. always returns empty map.
 func (p *Process) Threads() (map[string]string, error) {
 	ret := make(map[string]string, 0)
 	return ret, nil
 }
+
+// Times returns CPU times of the process.
 func (p *Process) Times() (*cpu.TimesStat, error) {
 	_, _, cpuTimes, _, _, err := p.fillFromStat()
 	if err != nil {
@@ -205,9 +242,15 @@ func (p *Process) Times() (*cpu.TimesStat, error) {
 	}
 	return cpuTimes, nil
 }
+
+// CPUAffinity returns CPU affinity of the process.
+//
+// Notice: Not implemented yet.
 func (p *Process) CPUAffinity() ([]int32, error) {
 	return nil, common.ErrNotImplementedError
 }
+
+// MemoryInfo returns platform in-dependend memory information, such as RSS, VMS and Swap
 func (p *Process) MemoryInfo() (*MemoryInfoStat, error) {
 	meminfo, _, err := p.fillFromStatm()
 	if err != nil {
@@ -215,6 +258,8 @@ func (p *Process) MemoryInfo() (*MemoryInfoStat, error) {
 	}
 	return meminfo, nil
 }
+
+// MemoryInfoEx returns platform dependend memory information.
 func (p *Process) MemoryInfoEx() (*MemoryInfoExStat, error) {
 	_, memInfoEx, err := p.fillFromStatm()
 	if err != nil {
@@ -223,6 +268,7 @@ func (p *Process) MemoryInfoEx() (*MemoryInfoExStat, error) {
 	return memInfoEx, nil
 }
 
+// Children returns a slice of Process of the process.
 func (p *Process) Children() ([]*Process, error) {
 	pids, err := common.CallPgrep(invoke, p.Pid)
 	if err != nil {
@@ -242,6 +288,8 @@ func (p *Process) Children() ([]*Process, error) {
 	return ret, nil
 }
 
+// OpenFiles returns a slice of OpenFilesStat opend by the process.
+// OpenFilesStat includes a file path and file descriptor.
 func (p *Process) OpenFiles() ([]OpenFilesStat, error) {
 	_, ofs, err := p.fillFromfd()
 	if err != nil {
@@ -255,15 +303,20 @@ func (p *Process) OpenFiles() ([]OpenFilesStat, error) {
 	return ret, nil
 }
 
+// Connections returns a slice of net.ConnectionStat used by the process.
+// This returns all kind of the connection. This measn TCP, UDP or UNIX.
 func (p *Process) Connections() ([]net.ConnectionStat, error) {
 	return net.ConnectionsPid("all", p.Pid)
 }
 
+// NetIOCounters returns NetIOCounters of the process.
 func (p *Process) NetIOCounters(pernic bool) ([]net.IOCountersStat, error) {
 	filename := common.HostProc(strconv.Itoa(int(p.Pid)), "net/dev")
 	return net.IOCountersByFile(pernic, filename)
 }
 
+// IsRunning returns whether the process is running or not.
+// Not implemented yet.
 func (p *Process) IsRunning() (bool, error) {
 	return true, common.ErrNotImplementedError
 }
@@ -687,6 +740,7 @@ func (p *Process) fillFromStat() (string, int32, *cpu.TimesStat, int64, int32, e
 	return terminal, int32(ppid), cpuTimes, createTime, nice, nil
 }
 
+// Pids returns a slice of process ID list which are running now.
 func Pids() ([]int32, error) {
 	var ret []int32