Angles are L-shaped structural steel represented by dimension of sides & thickness. For e.g. 50x50x6 means, both the sides of angles are 50mm & thickness is of 6mm. There are various sizes of angles which are as follows
:-( there are also equal & unequal angles)

Equal angles: - They are angles having both the sides of equal dimensions.
For e.g. refer below given diagram, in which both the sides are of dimensions "a".

SAIL (Steel Authority of India Limited)

Section	Dimensions	Sectional Weight	Length
	mm	kg/m	m
Angles
	Bhilai Steel Plant
	50 x 50 x 5*	3.8	10 to 13
	50 x 50 x 6	4.5	for all dimensions
	60 x 60 x 5/6/8*	4.5/5.4/7.0
	65 x 65 x 5*	4.9
	65 x 65 x 6/8/10	5.8/7.7/9.4
	70 x 70 x 5/6*	5.3/ 6.3
	75 x 75 x 5/ 6/ 8/ 10	5.7/6.8/8.9/11.0
	80 x 80 x 6/8/10	7.3/9.6/11.8
	90 x 90 x 6/8/10	8.2/10.8/13.4
	Dimensions	Sectional Weight	Length
	mm	kg/m	m
Angles	Durgapur Steel Plant
	100 x 100 x 10/12	14.9/17.7	10 to 11.5 for all dimensions
	110 x 110 x 10/12	16.6/19.7
	130 x 130 x 10/12	19.7/23.5
	150 x 150 x 12/16	22.9/27.3
	Bhilai Steel Plant
	150 x 150 x 16/ 20*	35.8/44.1	10 to 13
	200 x 200 x 16	48.5	for all dimensions
	200 x 200 x 20	60
	200 x 200 x 24	70.8

Channel is represented by its Web height & Flange width of the channel.

For e.g. 200x75 channel means, the Web height = 200mm & Flange width = 75mm.

Following are the sizes of Channel:-

Size	Weight in Kgs.	Weight in Kgs.
in mm	Per Feet	Per Mtr.
75 x 40	2.172	7.126
100 x 50	2.925	9.597
125 x 65	3.992	13.098
150 x 75	5.120	16.799
175 x 75	5.973	19.597
200 x 75	6.796	22.298
250 x 80	9.326	30.599
300 x 90	11.063	36.298
400 x 100	15.270	50.300

I - BEAM
It is represented by dimensions of Web & Flange. For e.g. 150x75 beam means,
Width of Web = 150mm
Width of Flange = 75mm

H - BEAM
In H-Beam generally the sizes of the Web & Flange are almost equal.
When we say, 254 x 254 beam means Web = 254mm & Flange = 254mm.